87 R10 stalls immediately after starting - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Bruno13 · 08-28-2017, 10:11 AM

Hi, I don't post often, if ever, but could use some advice.
Bought a 87 R10 2WD recently. Owner said not to use passenger side gas tank (later found out because it had a hole in it). Truck was running great on driver side tank. I decided to replace the in dash fuel tank selector switch because it looked like crap. With the new switch in, I switched back and forth on the tanks and it would only fire up after a little cranking, then sputter out. The switch was junk and I thought I may have had the tanks reversed, so I put the old switch back in. Same problem. I can hear the fuel pump. I can get it to start, but not say running without doing a lot of feathering of the gas pedal, then it eventually dies after 30 seconds or so.
My theory is that I may have picked up some sediment or other crap from the unused fuel tank, or that tanks fuel line, and clogged up my fuel filter.
I'm guessing the fuel pump relay and pump itself are ok. If I dump a little gas down the carb, it runs fine for a bit. Just seems to be starving on fuel after starting. It is a TBI carb.
Also, the oil pressure gauge does not work. I started to try and replace the oil pressure switch/sender by the distributor, but gave up as it was virtually inaccessible. I know that acts as a back up for the fuel pump relay, but it was running fine before. Only other thing I did was go through and check all the fuses before changing the switch. I have 2 fuses with no juice. One is at the bottom labeled INJ 3A, and the other is dash lights 10A. Neither of these are getting any voltage. I assume they were bad before this issue, but curious what the INJ fuse it. Injectors?
I'm hoping I just need to change the fuel filter.
Any advice from anyone is certainly appreciated.

Thanks,
Dave

D13 · 08-28-2017, 01:40 PM

The ECM fires the fuel pump relay to build pressure fuel for start up. Once running, the ECM drops the circuit and the relay is fed by the oil pressure switch being closed. If the switch is bad, unplugged, cut wire, or no oil pressure, no signal to the relay and no fuel is pumped. Once the start up pressure is gone the engine stalls.
My bet is if you measure voltage to the pump it goes ot zero once running, indicating the oil pressure switch is bad or disconnected.
If the pump is getting power, then the in-tank sock or filter, or a tired pump, are most likely.

Bruno13 · 08-28-2017, 04:34 PM

Thank you so much for the reply. I did have a guy working on the oil pressure switch and we gave up on it because I was afraid to pull the distributor to access it. There's a chance he forgot to hook it back up, I hope.
I'm going to pop a new fuel filter in it anyway for $6. Couldn't hurt anything.
I'll let you know how it comes out.
Thanks again,
Dave

Bruno13 · 08-28-2017, 07:35 PM

I checked the oil sender switch today and it is connected. I'm talking about the one next to the distributor with 2 prong hook up. I understand there is another sender/switch by the oil filter that controls the gauge. My gauge also doesn't work and sits at about 10lbs. It does move when I turn the truck off or on though. This gauge issue was like this when I bought the truck so I know that is not what is causing it to stall.
Replacing in line fuel filter in a.m.
Also, I have a fuse at the bottom of the block labeled INJ and it is 3A. No power at all to it. Replaced fuse, etc. I think this was blown when I bought the truck, but can not be certain. Does anybody know what this is for?
Like I said, I can get the truck to fire up, but only for a few seconds and it sputters out.
Getting frustrated because it ran great just the other day until I tried to replace the in-dash fuel tank selector switch.
Help?

xs-style · 08-28-2017, 08:21 PM

Two thought for ya...

Take the line loose in coming into your filter. Put a piece of hose on it and run the hose to a jug. Then have someone try to start the truck. You should be able to tell if the pump it's working as it should.

Get up under the truck and put your hand on the tank as close to the pump as possible. Not likely..but the tank selector could be stuck on the wrong tank?

Bruno13 · 08-29-2017, 04:33 PM

I checked the fuel pump and it is definetly working on driver side. Also replace in line fuel filter today hoping it was clogged up. No difference. Putting new oil pressure switch in tomorrow. Hopefully that is it.

xs-style · 08-29-2017, 08:02 PM

Sounds like it would about have to be that. Pump runs off the relay for 5-10 seconds, then off the oil pressure switch. Sometimes you can get a crows foot on that switch if it's vertical, or a set of ratcheting pliers on it if it's off an elbow. Good luck with it.

RUN GMC · 08-31-2017, 03:33 AM

Like the above was stated....but you might want also check out the plug/wiring to the oil pressure switch if the change out doesnt fix the problem............

Mattchu60 · 08-31-2017, 08:35 AM

I have a TBI truck as well. Mine did something similar 2 months ago. It died. It would start after a lot of cranking and then die. If I pumped the gas once it fired it would stumble and hardly run.

The fuel pump was "dying" - i put a gauge on it and only had 1-2 lbs of pressure. New pump solved it.

Bruno13 · 08-31-2017, 09:35 AM

Thanks for everyones input. Replaced the oil pressure sender by the distributor yesterday, breaking off that damn brass nipple in the process. Trip to Lowes and cobbled something together. No change, however, I probably fixed that nasty oil leak at the fitting.
This morning I am picking up the oil pressure gauge switch at NAPA. My gauge didn't work anyway. While removing the old one, another hard and damn greasy job, we test the gauge by shorting the wire out, and it did go over to 60 lbs. If this doesn't fix it, maybe at least the damn gauge will work.
I was hoping to get it running so we can put it up on the lift. The passenger fuel tank is shot so am putting a new one in with a new pump/sender.
We'll be taking the bed off because I've done it before with the bed on and it's a *****. If need be, while I have it off, I'll have decent access to the driver (good tank) where I can check that pump as well. Never mentioned, but the gauge shows full and doesn't deviate at all when switching tanks.
This is becoming a pain in the you know what, especially seeing it ran fine one day, and not the next. The only other things we did before it broke were to change the oil and the thermostat gasket.
Still looking for that "magic suggestion" if someone wants to chime in. I'm praying the new oil pressure switch does the trick.

Katrina/10 · 08-31-2017, 12:56 PM

The oil pressure switch is just a backup for the relay. The ECM energizes the relay when it sees pulses from the distributor. Your pump is probably bad or the hose in the gas tank ruptured.

Bruno13 · 08-31-2017, 04:42 PM

Thanks Gary. It couldn't just be the fuel pump relay then could it? too easy, I"m sure. Plus, I am hearing the fuel pump come on with the ignition. Everything I"ve seen in the forum makes it sound like the fuel pump is cutting out after a second or two. Acts like something is telling the fuel pump to cut off. Many ideas pointed to the oil pressure sender/switches.
At any rate, putting the other one on tomorrow that will hopefully fix the issue, or at least get the op gauge working again. Thanks.

Katrina/10 · 08-31-2017, 05:14 PM

If you can hear the fuel pump run, the relay is good. As others have said, it will only run for 2 seconds if you do not start the engine. There is a small white wire on the fuel pump relay that will allow the pump to run constantly if you connect it to 12 volts. It's there to test the pump.

The pump may run, but not put out the correct pressure. The best way to check it is to get under the truck and disconnect the fuel filter, then connect a pressure gauge.

Bruno13 · 09-03-2017, 09:11 AM

The saga continues...
Installed a new fuel tank, sender, and fuel pump, and a 2nd new fuel filter. Blew out line from carb back. Confirmed pump is running. Same thing. Cuts off after 2 seconds. Not much else to replace. We even bypassed the fuel tank selector and took a line direct from the tank to the fuel filter. No change.
All I can guess is some stupid wiring issue. When I bought the truck, you can tell the wiring had been worked on here and there. There was one group of wires going directly into the TBI carb base from the front. It had been cut and each wire was taped up with electrical tape. It looked terrible so I put a plastic loom over it to conceal it. I am starting to wonder if somehow I had detached one of the wires (under the electrical tape) while putting the loom over it?? There is about 5 or 6 wires in this group. I'm checking this morning. I had a NASCAR driver and a long time mechanic help me with it for 4 hours yesterday, to no avail.
Any new thoughts from anybody??
Thanks

Katrina/10 · 09-03-2017, 10:06 AM

I believe the wires you're talking about are to the fuel injectors, should be four wires. Take a look at the injectors with someone cranking/running the engine, are both injectors spraying fuel?

Bruno13 · 09-03-2017, 04:22 PM

Thanks Gary. Yes, both were spraying on initial start up, and longer if we kept feathering the throttle. At least until this morning when I tried to screw something else up

Wiring on this truck has been messed with for years when I bought it. Lots of splices with electrical tape, even some with masking tape! The 4 wires we discussed, the injector wires, had all been spliced. When my problems started happening, I tried to recall everything I touched before the "no start" problem. One of them was putting these 4 wires into a plastic loom to make it look better. While pondering last night, I thought I would check each of the connections of these wires today. I took the loom off, unspliced each of the wires, respliced them correctly, and put heat shrink on each connection. Somehow, in doing this, I screwed up something else. Went to start the truck and it tried to fire up twice, like it has been, then wouldn't fire at all. Tried to fire it off original working gas tank, and nothing. Come to find out I had a big gas puddle under truck because fuel switch was not connected because we bypassed it yesterday. Doohhh! Hooked fuel selector valve up again, and still no attempt to fire at all.
Next, I checked the fuses. I have a fuse labeled ECMB 10A which was blown. This never blew before. I replaced it, and it blew immediately upon cranking again. Moved to 15A fuse, same thing.
Checked under hood again and noticed a pretty crappy ground wire coming out of the ECM? harness and grounding on the Alt bracket, along with another ground. It had been spliced twice, was oily, and ground bolt was loose, so I thought I found my culprit. Put on new connector, cleaned up ground, and NO change once again. No injector spray at all, and fuse still blows.
Im not sure what I could have done just by resplicing those 4 wires, and cleaning up a ground, to make this keep popping a fuse. Even with fuse blown, I could hear fuel pumps working, so those, and the fuel relay must still be ok. Just no power to injectors now.
I've posted some pics of the wiring, ground connection, etc. If anyone has a clue of what is going on, please chime in. I'm moving backwards on this project and I'm willing to bet it is just something simple and stupid.
Thanks
OOPs. can't post pics because they are on my hard drive, not the web.

08-28-2017, 10:11 AM	#1
Bruno13 Registered User Join Date: Jul 2014 Location: Mooresville, NC Posts: 20	87 R10 stalls immediately after starting Hi, I don't post often, if ever, but could use some advice. Bought a 87 R10 2WD recently. Owner said not to use passenger side gas tank (later found out because it had a hole in it). Truck was running great on driver side tank. I decided to replace the in dash fuel tank selector switch because it looked like crap. With the new switch in, I switched back and forth on the tanks and it would only fire up after a little cranking, then sputter out. The switch was junk and I thought I may have had the tanks reversed, so I put the old switch back in. Same problem. I can hear the fuel pump. I can get it to start, but not say running without doing a lot of feathering of the gas pedal, then it eventually dies after 30 seconds or so. My theory is that I may have picked up some sediment or other crap from the unused fuel tank, or that tanks fuel line, and clogged up my fuel filter. I'm guessing the fuel pump relay and pump itself are ok. If I dump a little gas down the carb, it runs fine for a bit. Just seems to be starving on fuel after starting. It is a TBI carb. Also, the oil pressure gauge does not work. I started to try and replace the oil pressure switch/sender by the distributor, but gave up as it was virtually inaccessible. I know that acts as a back up for the fuel pump relay, but it was running fine before. Only other thing I did was go through and check all the fuses before changing the switch. I have 2 fuses with no juice. One is at the bottom labeled INJ 3A, and the other is dash lights 10A. Neither of these are getting any voltage. I assume they were bad before this issue, but curious what the INJ fuse it. Injectors? I'm hoping I just need to change the fuel filter. Any advice from anyone is certainly appreciated. Thanks, Dave

08-28-2017, 01:40 PM	#2
D13 Registered User Join Date: Feb 2007 Location: Memphis MI Posts: 1,851	Re: 87 R10 stalls immediately after starting The ECM fires the fuel pump relay to build pressure fuel for start up. Once running, the ECM drops the circuit and the relay is fed by the oil pressure switch being closed. If the switch is bad, unplugged, cut wire, or no oil pressure, no signal to the relay and no fuel is pumped. Once the start up pressure is gone the engine stalls. My bet is if you measure voltage to the pump it goes ot zero once running, indicating the oil pressure switch is bad or disconnected. If the pump is getting power, then the in-tank sock or filter, or a tired pump, are most likely. __________________ 1987 2 ton 1982 250/TH350 beater in progress Dad's 1981 3/4 L6 3 on tree posi and no options, awaiting restoration or scrapping Plus a mess o' tractors

08-28-2017, 04:34 PM	#3
Bruno13 Registered User Join Date: Jul 2014 Location: Mooresville, NC Posts: 20	Re: 87 R10 stalls immediately after starting Thank you so much for the reply. I did have a guy working on the oil pressure switch and we gave up on it because I was afraid to pull the distributor to access it. There's a chance he forgot to hook it back up, I hope. I'm going to pop a new fuel filter in it anyway for $6. Couldn't hurt anything. I'll let you know how it comes out. Thanks again, Dave

08-28-2017, 07:35 PM	#4
Bruno13 Registered User Join Date: Jul 2014 Location: Mooresville, NC Posts: 20	Re: 87 R10 stalls immediately after starting I checked the oil sender switch today and it is connected. I'm talking about the one next to the distributor with 2 prong hook up. I understand there is another sender/switch by the oil filter that controls the gauge. My gauge also doesn't work and sits at about 10lbs. It does move when I turn the truck off or on though. This gauge issue was like this when I bought the truck so I know that is not what is causing it to stall. Replacing in line fuel filter in a.m. Also, I have a fuse at the bottom of the block labeled INJ and it is 3A. No power at all to it. Replaced fuse, etc. I think this was blown when I bought the truck, but can not be certain. Does anybody know what this is for? Like I said, I can get the truck to fire up, but only for a few seconds and it sputters out. Getting frustrated because it ran great just the other day until I tried to replace the in-dash fuel tank selector switch. Help?

08-28-2017, 08:21 PM	#5
xs-style Registered User Join Date: Mar 2008 Location: Lawndale, NC Posts: 658	Re: 87 R10 stalls immediately after starting Two thought for ya... Take the line loose in coming into your filter. Put a piece of hose on it and run the hose to a jug. Then have someone try to start the truck. You should be able to tell if the pump it's working as it should. Get up under the truck and put your hand on the tank as close to the pump as possible. Not likely..but the tank selector could be stuck on the wrong tank?

08-29-2017, 04:33 PM	#6
Bruno13 Registered User Join Date: Jul 2014 Location: Mooresville, NC Posts: 20	Re: 87 R10 stalls immediately after starting I checked the fuel pump and it is definetly working on driver side. Also replace in line fuel filter today hoping it was clogged up. No difference. Putting new oil pressure switch in tomorrow. Hopefully that is it.

08-29-2017, 08:02 PM	#7
xs-style Registered User Join Date: Mar 2008 Location: Lawndale, NC Posts: 658	Re: 87 R10 stalls immediately after starting Sounds like it would about have to be that. Pump runs off the relay for 5-10 seconds, then off the oil pressure switch. Sometimes you can get a crows foot on that switch if it's vertical, or a set of ratcheting pliers on it if it's off an elbow. Good luck with it. __________________ 1978 Scottsdale - celebrating 10 years of teaching me profanity 1990 Silverado - bought in Nov. 2016 and it's already catching up - Sold 1987 k5 blazer - sold... :\ seed money for the 81 1981 k20 4x4 - 5.3 swap in progress Events attended: Spring GOG 2011 Dale JR car show Summer 2012 Gathering at Tommys pickup parts

08-31-2017, 03:33 AM	#8
RUN GMC Registered User Join Date: May 2014 Location: North AL Posts: 363	Re: 87 R10 stalls immediately after starting Like the above was stated....but you might want also check out the plug/wiring to the oil pressure switch if the change out doesnt fix the problem............ __________________ http://i204.photobucket.com/albums/b...baae5d9a7e.jpg

08-31-2017, 08:35 AM	#9
Mattchu60 Registered User Join Date: Jan 2014 Location: Swaledale, IA Posts: 485	Re: 87 R10 stalls immediately after starting I have a TBI truck as well. Mine did something similar 2 months ago. It died. It would start after a lot of cranking and then die. If I pumped the gas once it fired it would stumble and hardly run. The fuel pump was "dying" - i put a gauge on it and only had 1-2 lbs of pressure. New pump solved it.

08-31-2017, 09:35 AM	#10
Bruno13 Registered User Join Date: Jul 2014 Location: Mooresville, NC Posts: 20	Re: 87 R10 stalls immediately after starting Thanks for everyones input. Replaced the oil pressure sender by the distributor yesterday, breaking off that damn brass nipple in the process. Trip to Lowes and cobbled something together. No change, however, I probably fixed that nasty oil leak at the fitting. This morning I am picking up the oil pressure gauge switch at NAPA. My gauge didn't work anyway. While removing the old one, another hard and damn greasy job, we test the gauge by shorting the wire out, and it did go over to 60 lbs. If this doesn't fix it, maybe at least the damn gauge will work. I was hoping to get it running so we can put it up on the lift. The passenger fuel tank is shot so am putting a new one in with a new pump/sender. We'll be taking the bed off because I've done it before with the bed on and it's a *****. If need be, while I have it off, I'll have decent access to the driver (good tank) where I can check that pump as well. Never mentioned, but the gauge shows full and doesn't deviate at all when switching tanks. This is becoming a pain in the you know what, especially seeing it ran fine one day, and not the next. The only other things we did before it broke were to change the oil and the thermostat gasket. Still looking for that "magic suggestion" if someone wants to chime in. I'm praying the new oil pressure switch does the trick.

08-31-2017, 12:56 PM	#11
Katrina/10 Registered User Join Date: Oct 2010 Location: Ocean Springs, MS Posts: 1,746	Re: 87 R10 stalls immediately after starting The oil pressure switch is just a backup for the relay. The ECM energizes the relay when it sees pulses from the distributor. Your pump is probably bad or the hose in the gas tank ruptured. __________________ Gary 1971 Chevrolet C/10 1951 GMC 100 1977 GMC C15 1955 Chevrolet 3100

08-31-2017, 04:42 PM	#12
Bruno13 Registered User Join Date: Jul 2014 Location: Mooresville, NC Posts: 20	Re: 87 R10 stalls immediately after starting Thanks Gary. It couldn't just be the fuel pump relay then could it? too easy, I"m sure. Plus, I am hearing the fuel pump come on with the ignition. Everything I"ve seen in the forum makes it sound like the fuel pump is cutting out after a second or two. Acts like something is telling the fuel pump to cut off. Many ideas pointed to the oil pressure sender/switches. At any rate, putting the other one on tomorrow that will hopefully fix the issue, or at least get the op gauge working again. Thanks.

08-31-2017, 05:14 PM	#13
Katrina/10 Registered User Join Date: Oct 2010 Location: Ocean Springs, MS Posts: 1,746	Re: 87 R10 stalls immediately after starting If you can hear the fuel pump run, the relay is good. As others have said, it will only run for 2 seconds if you do not start the engine. There is a small white wire on the fuel pump relay that will allow the pump to run constantly if you connect it to 12 volts. It's there to test the pump. The pump may run, but not put out the correct pressure. The best way to check it is to get under the truck and disconnect the fuel filter, then connect a pressure gauge. __________________ Gary 1971 Chevrolet C/10 1951 GMC 100 1977 GMC C15 1955 Chevrolet 3100

09-03-2017, 09:11 AM	#14
Bruno13 Registered User Join Date: Jul 2014 Location: Mooresville, NC Posts: 20	Re: 87 R10 stalls immediately after starting The saga continues... Installed a new fuel tank, sender, and fuel pump, and a 2nd new fuel filter. Blew out line from carb back. Confirmed pump is running. Same thing. Cuts off after 2 seconds. Not much else to replace. We even bypassed the fuel tank selector and took a line direct from the tank to the fuel filter. No change. All I can guess is some stupid wiring issue. When I bought the truck, you can tell the wiring had been worked on here and there. There was one group of wires going directly into the TBI carb base from the front. It had been cut and each wire was taped up with electrical tape. It looked terrible so I put a plastic loom over it to conceal it. I am starting to wonder if somehow I had detached one of the wires (under the electrical tape) while putting the loom over it?? There is about 5 or 6 wires in this group. I'm checking this morning. I had a NASCAR driver and a long time mechanic help me with it for 4 hours yesterday, to no avail. Any new thoughts from anybody?? Thanks

09-03-2017, 10:06 AM	#15
Katrina/10 Registered User Join Date: Oct 2010 Location: Ocean Springs, MS Posts: 1,746	Re: 87 R10 stalls immediately after starting I believe the wires you're talking about are to the fuel injectors, should be four wires. Take a look at the injectors with someone cranking/running the engine, are both injectors spraying fuel? __________________ Gary 1971 Chevrolet C/10 1951 GMC 100 1977 GMC C15 1955 Chevrolet 3100



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09-03-2017, 04:22 PM	#16
Bruno13 Registered User Join Date: Jul 2014 Location: Mooresville, NC Posts: 20	Re: 87 R10 stalls immediately after starting Thanks Gary. Yes, both were spraying on initial start up, and longer if we kept feathering the throttle. At least until this morning when I tried to screw something else up Wiring on this truck has been messed with for years when I bought it. Lots of splices with electrical tape, even some with masking tape! The 4 wires we discussed, the injector wires, had all been spliced. When my problems started happening, I tried to recall everything I touched before the "no start" problem. One of them was putting these 4 wires into a plastic loom to make it look better. While pondering last night, I thought I would check each of the connections of these wires today. I took the loom off, unspliced each of the wires, respliced them correctly, and put heat shrink on each connection. Somehow, in doing this, I screwed up something else. Went to start the truck and it tried to fire up twice, like it has been, then wouldn't fire at all. Tried to fire it off original working gas tank, and nothing. Come to find out I had a big gas puddle under truck because fuel switch was not connected because we bypassed it yesterday. Doohhh! Hooked fuel selector valve up again, and still no attempt to fire at all. Next, I checked the fuses. I have a fuse labeled ECMB 10A which was blown. This never blew before. I replaced it, and it blew immediately upon cranking again. Moved to 15A fuse, same thing. Checked under hood again and noticed a pretty crappy ground wire coming out of the ECM? harness and grounding on the Alt bracket, along with another ground. It had been spliced twice, was oily, and ground bolt was loose, so I thought I found my culprit. Put on new connector, cleaned up ground, and NO change once again. No injector spray at all, and fuse still blows. Im not sure what I could have done just by resplicing those 4 wires, and cleaning up a ground, to make this keep popping a fuse. Even with fuse blown, I could hear fuel pumps working, so those, and the fuel relay must still be ok. Just no power to injectors now. I've posted some pics of the wiring, ground connection, etc. If anyone has a clue of what is going on, please chime in. I'm moving backwards on this project and I'm willing to bet it is just something simple and stupid. Thanks OOPs. can't post pics because they are on my hard drive, not the web.

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