Fuel pump options
 

1969 GMC C15 w/ 230 straight 6

Ok, folks. Need some advice here.

I'm having a heck of a time trying to figure out why the pump isn't sending any fuel. Replaced old pump back in January and it worked fine. Didn't touch the truck again until a few weeks ago and found the pump wasn't functioning. It was under warranty so I slapped a new one in and it's not working either.

I even tried running a line directly from a portable tank to the pump inlet and still no joy. Am I missing something obvious?

On a related note....do I have an option of converting over to an electric pump? If the price is right and the install is easy, I'm kinda liking the idea of ditching the mechanical pump.

Your input is greatly appreciated. Thanks

Re: Fuel pump options
 

mechanical fuel pump are about the most reliable thing in the wholedamn truck

check the fuel lines in the gas tank for blockage at the sock on the sender unit

Re: Fuel pump options
 

Not much help on straight 6's. Do they have the bolt that holds the rod in the engine while you swap it out right? Is it possible someone had the bolt too tight and rounded the lobeoff cam?

Re: Fuel pump options
 

Ok, bear with me here. I'm a newbie to this so it'll likely end up that I did something stupid.....

Is there actually an actuator rod involved here? I did some reading earlier and that seemed to be a V8 thing (if I read it correctly). My limited research says the pump on my L6 works via a lobe on a cam. Again, I could be wrong here.

I didn't do anything special when I put the pump in last January. Just bolted it on and it worked fine. So I didn't do anything special when I installed this pump a few weeks ago.

I checked for suction at the inlet and got nothing. I also ran a line straight from a portable gas can straight to the pump and still nothing.

Re: Fuel pump options
 

I've known from day 1 that the stock tank is toast so I'm just been using a portable gas can with new line ran to the hard line that runs along the frame.

I did verify my new hose has no blockages as well as the line from the pump to the carb. All clear.

Re: Fuel pump options
 

Sounds like a bad pump the 8 cyl trucks do have a pushrod the 6 cyl do not. It is very possible that the new pump is toast specialty if it is/was a cheaper parts store type pump. You can put in an electric pump but then you'll need a regulator and have to listen to the thing rattle and make all the noise it does.

Re: Fuel pump options
 

Can't recall the make of pump. Picked it up at O'Reilly's. Should I buy somewhere else? Get a specific brand?

Also, nothing special to do when installing it right? Just take the old one off and bolt the new one on.

Finally, if I wanted to run a quick test once I install yet another pump, just I be able to feel some suction if I put my finger over the inlet port?

Sorry for all of the questions, just don't want to miss anything or make an incorrect assumption on something.

thanks

Re: Fuel pump options
 

x2

I've had cheapo mechanical pumps fail pretty rapidly in succession.

went out and paid double for one and it has worked for over 4 or so years without failure.

Make sure your tank is not supplying dirty fuel. no pump can be expected to handle that for very long

Re: Fuel pump options
 

Any suggestions on a good pump?

Fuel is fine. As I mentioned earlier, I'm using a portable tank w/ fresh gas, with a new line running from it to the pump.

Re: Fuel pump options
 

I don't know if this will be helpful or not. But, when I bought my C-20 in 2003 the mechanical fuel pump was leaking. So I bought a new one in order to make the 150 mile trip home. Only it suddenly didn't work, at all. The leaking pump worked fine, but the new one didn't. So, as a stop-gap, I bought an electric pump, put it inline and bypassed the mechanical pump. I kid you not, I've been running the truck like that ever since.
I now know that the pushrod for the fuel pump isn't working properly, and has likely worn out all together (or the cam that is). But the electric pump hasn't failed once in the past 12 years. I didn't put in a pressure regulator, and just count on the float valve in the carb to cut off fuel when necessary.

Re: Fuel pump options
 

Is there an easy way to tell whether or not the lobe on the cam has given up the ghost? If so, I'd like to rule that out as a possible issue before I just slap another pump on it.

Re: Fuel pump options
 

No, there really isn't an easy way to check without pulling the cam.

If you had a buddy that could crank the engine by hand, you could put a dab of grease on the end of the pushrod, place your finger on the other end, and attempt an eyeball measurement to the distance it travels, or build some measurement contraption to check it. I think that would be overkill though.

It would be highly unlikely that the cam lobe would have worn away, as a stock or similar pump doesn't have enough spring pressure to grind away the cam unless there was no lubrication. If there were no oil, the entire motor would have seized before just the fuel pump cam lobe.

I'm not saying it's not possible, but that would be a weird set of circumstances.