Fuel pump replacement?

[jabborabbo]

‘67 GMC 250 L6 engine. Drove the truck to another town and took the opportunity to fill it up with premium non-ethanolic gas (it’s been a couple of months since the tank has been full - I’ve been buying local regular non-ethanolic a few gallons at a time). I get home, park it, truck has run fine the whole time...then the garage smells of gasoline. I don’t see any problem with the inlet or outlet lines on the pump, but the bottom of the pump has gas on it - not dripping off, just oozing out apparently.

So it’s the pump, right? I know replacing it is straightforward job - does anyone have any tips?

Thanks!

[ncpetersc]

Very straightforward, the only semi-difficult part was trying to hold the pushrod in place when installing the new one. I used a tongue depressor sized piece of spring steel, which helped.

This guy used a screwdriver: https://www.youtube.com/watch?v=8XiuiyBAD8Q

[Stocker]

Dunno about L6 engines, but small-blocks have a threaded hole you can run a bolt into to hold the pushrod while you bolt the fuel pump on.

[68 P.O.S.]

What carb are you running?

[jabborabbo]

Originally Posted by 68 P.O.S.

What carb are you running?

Rochester B...I rebuilt it a few weeks ago and the truck runs better than it has since I got it. It seems that over the 5 years I’ve had it, anytime I repair or rebuild something, a system-related problem crops up in a few weeks...replaced the radiator and the water pump quit...rebuild the carb and the fuel pump starts leaking....

But it’s all fun, in a slightly masochistic way.

[truckster]

But I have to ask... Why premium? Unless you're running high compression in that engine it's probably not giving you any benefit. If you haven't had detonation with regular, I would run that and fill the tank more regularly. A full tank helps prevent condensation.

[RichardJ]

The pump arm on a L6 pump runs directly on the cam lobe. No push rod.
As with any leaking fuel pump, sniff the oil on the dip stick. The gas can run into the engine and you need to change the oil and filter. NOW.

The old pumps i have pulled off had a tab riveted to the pump arm. I believe it to be a sacrificial metal to prevent wear on the cam pump lobe. The new Carter pumps don't have the tab. I spent time finding out that Airtex pumps still have the tab. i spent more time and gas getting an Airtex from the Truck Shop. I tested it before installation and found that the pressure dropped between successive pump strokes.

I then bought a Carter from NAPA. It pumped to 4 psi on the first stroke and stayed there on every successive pump cycle.

[VWNate1]

As mentioned, a new pump should set you right again .

Premium fuels because the bilge they're selling these days isn't anywhere near as good as regular was when your truck was designed and built .

Yes, it co$t$ more but the low compression engine will run better anf less damage to carby, fuel pump diaphragm and so on .

Those who are either cheapskates or don't know, will tell you no need to run premium fuels .

Luckily these pumps are still made and not expen$ive to buy .

[jabborabbo]

Originally Posted by truckster

But I have to ask... Why premium? Unless you're running high compression in that engine it's probably not giving you any benefit. If you haven't had detonation with regular, I would run that and fill the tank more regularly. A full tank helps prevent condensation.

I suppose I use premium because back when my truck was new, regular (obviously leaded) was 93 or 94 octane. I haven’t noticed any detonation with today’s regular, but I also have hearing loss.... Perhaps it’s mild paranoia that makes me do it. I appreciate your comment regarding keeping the tank full - that may ease my obsession. Thanks!

[jabborabbo]

Originally Posted by RichardJ

The pump arm on a L6 pump runs directly on the cam lobe. No push rod.
As with any leaking fuel pump, sniff the oil on the dip stick. The gas can run into the engine and you need to change the oil and filter. NOW.

The old pumps i have pulled off had a tab riveted to the pump arm. I believe it to be a sacrificial metal to prevent wear on the cam pump lobe. The new Carter pumps don't have the tab. I spent time finding out that Airtex pumps still have the tab. i spent more time and gas getting an Airtex from the Truck Shop. I tested it before installation and found that the pressure dropped between successive pump strokes.

I then bought a Carter from NAPA. It pumped to 4 psi on the first stroke and stayed there on every successive pump cycle.

I’ve sniffed the oil - there’s no gas smell. The replacement I bought is a Delphi that doesn’t have the sacrificial metal on it - I haven’t put it in yet - I could get an AC Delco if you think I should....

[jabborabbo]

Originally Posted by VWNate1

As mentioned, a new pump should set you right again .

Premium fuels because the bilge they're selling these days isn't anywhere near as good as regular was when your truck was designed and built .

Yes, it co$t$ more but the low compression engine will run better anf less damage to carby, fuel pump diaphragm and so on .

Those who are either cheapskates or don't know, will tell you no need to run premium fuels .

Luckily these pumps are still made and not expen$ive to buy .

Yes! Thanks!

[VWNate1]

Don't ever let anyone talk you out of that 250 ! .

Most are shocked when they ride in my '69, the engine is loosey-goosey but runs out very strongly because I keep it in sharp tune .

I'd hot change the oil and filter the *instant* I finished the replacement of that old pump .

Remember to hold the new pump up next to the old one, the out side isn't terribly important as long as the pipes connect but the lever *must* match excatly of the new pump won't last long .

Spend some time looking at NAPA, Rock Auto etc. before buying a cheap Delphi part ~ GM sold off AC / DELCO some years ago so new Delphi stuff is in now way as good .

Lots and lots of N.O.S. fuel pumps out there plus Airtex, NAPA and so on .

[VWNate1]

Let's see if I can add these Rock Auto part #'s :

CARTER M4503 {#6416502, 6440616} Mechanical Pump Info
Crimp Style Sheet Metal Housing

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Part image
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$15.54
Add to Cart
DELPHI MF0051 {#6416502, 6440616} Mechanical Pump Info
2 Line Pump; Stamped steel fuel pump

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Part image
>
$15.86
Add to Cart
AIRTEX 40446 Mechanical Pump Info One of our most popular parts

See ? cheap and easy, just like my High School girlfriend.....

[Steeveedee]

Don't knock cheap and easy! Just a waggle of the eyebrows, and it's on!

[bill3rail]

Originally Posted by RichardJ

The pump arm on a L6 pump runs directly on the cam lobe. No push rod.

That makes the job too simple!

[VWNate1]

I was driving down Figurative St. in South Central Los Angeles this afternoon, and boy howdy was there some smoking hot easy strutting , not sure how cheap but zowie .

[truckster]

Originally Posted by VWNate1

.

Those who are either cheapskates or don't know, will tell you no need to run premium fuels .

API and every major automotive manufacturer disagrees with you, but what do a bunch of mechanical and chemical engineers know? Yes, non-ethanol is better for your fuel system, but premium fuel is a designation for higher octane, which most engines neither need nor derive any benefit from.

[jabborabbo]

Got ‘er done! Thanks to all for the advice and entertainment!

[VWNate1]

They don't in fact say that but who cares when you're not interested in facts, right ? .