Hi folks, can anyone recommend a suitable replacement mechanical fuel pump that worked well with their 300 six? This is a '79.

I recently replaced all my fuel lines; without knowing how old the pump was and due to the fact that it sat dry for a long time (since this project ended up taking longer than expected), I opted to replace the pump too, but I'm starting to wish I hadn't. The first replacement was a Carter; I installed it only to find the inlet barb was the wrong size (5/16" instead of 3/8") Next was a unit from Napa (correct inlet size) which appeared visually identical to the previous pump.

I cannot get the flare fitting on the outlet of the pump to seal. Fuel bubbles between the line and the nut, leading me to believe the flare is not making. I inspected the flare surface of the new line (bought new, not hand-made) and see no flaws. I installed the original factory (known-good) line, and that one leaks like a sieve. I can only suspect the pump at this point. The pump's flare surface looks fine, but perhaps the machined angle is off. I've ran into similar situations with wheel cylinders.

What replacement brand has worked for you? I see the Airtex model listed as the most popular option on RockAuto's website, but wanted to ask here first. I understand that an electric pump is an alternative, but not an option I'm interested in pursuing. Thanks for your help.

 

I have always had good luck with airtex pumps in the past. I have not needed to replace the pump on my 300 in the 16 years I've had it, so I cannot speak about this particular model of pump. I did replace the pump on the 390 with an airtex brand a couple years back, and it's still going strong.

 

Thanks Rogue; that information alone is very helpful.

 

If I understand you correctly this is the line from the pump to the carb? Can't help much on the actual pump although I will be looking at airtex if I ever need another! Had the same problem when I switched out the intake and carb on my 6 so changed the outlet on the pump to a nozzle style and ran rubber fuel line to the carb. Not as good as hard lines but much easier to deal with. Plus you can add another filter if you want to.
Good Luck!

 

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Sorry to not know the exact model, but when my 89 F150 I6 4.9 was rebuilt there were several other changes to the vehicle. One was a new fuel tank and extended pump. The pump installed in the tank by the machine shop was from a ..... Chevrolet... (there, I said it.). The reason given was that this pump was a lot more robust and likely to last longer. They handed me both pumps, and the chev pump was noticeably more heavy and they attributed the difference to the materials used in the construction of the motor. So I blessed them and forward they went. The new pump hits 55lbs pre-injectors as soon as you turn on the key.
Don't know if this helps, but I'd have never thought of it on my own and never heard of it before.
Just my 2c worth on the subject.

 

Thanks guys. To be clear, being a '79, this would be a carbureted fuel pump, so we're looking at 5 to 7 PSI. I plan on going with the Airtex pump. I appreciate all the feedback; this thread was really helpful.

 

Well, no go on the Airtex, and a follow-on generic brand from O'Reilly's either. All have the same problem: either the inlet is the wrong size, or the outlet leaks. In the case of the latter, the flare seat seems too soft. Even if you're gentle and tighten the flare just enough to normally make a proper seal, the cone gets scraped. I think these are just cheap pumps.

I haven't had any success with replacement mechanical pumps it seems, so I'm going electric. I've heard good things about the Carter P4070, and it looks like it'll fit snug inside the frame rail. We'll see how it goes.

 

I have had bad luck with Napa fuel pumps. They either fail right away or leak like yours. I put an airtex pump from auto zone on my 79 300 awhile back and no problems. Was made in USA even. But then I put one on an OT car and the fitting leaked. Retuned for exchange and 2nd one the same.3rd one finally worked.
Just low quality machining or a bad batch maybe?

 

I imagine so. Thanks for chiming in; sorry to hear you've had similar troubles, but at least now I know I'm not the only one.

 

Just following up with the final conclusion in case anyone is interested. I did convert to an electric fuel pump as described in my previous post, and I'm pleased with the results. No more crummy replacement fuel pumps.

Since I hang out in the 73-79 forum more, I posted my write-up there. Here's a link in case anyone is interested (apologies for the cross-post).

https://www.ford-trucks.com/forums/1...sion-pics.html