Hi All,

Greeting from the C-3 contingent. There has probably been many threads on this topic and I apologize for not just doing a search but here goes. I have an 82 in tank pump/sender unit in my injected 80 C-3. With the new 420 ci SBC I am experiencing fuel starvation above 5,000 rpm. I had a 255 HP Walbro pump recommended to me and I have also heard they are very noisy.

1. Anyone willing to voice an opinion or option on eliminating the fuel starvation.
2. What is the recommended feed and return line size for a 537HP (at flywheel) engine?

Many thanks,

Ken

 

Ken an in the tank walbro 255 EFI pump will not produce any more noise than a stock TPI pump. At least that is from my experience. As for a fuel line size for what you are running a 3/8 line would probably suffice. I have seen many 3/8 lines supporting 500+ in a lot of F bodies and even my own personal C4 with a 396 LT4 with a blower. Its putting down over 500 at the rear wheels. A lot of people would say do a 1/2 inch line and by the book that's correct. I am just saying with my car and others I have worked on I haven't had any issues with fuel starvation. If I were you I would stay with the 3/8 feeder and the 5/16 return line with the larger walbro and try it before ripping it all out and going with a 1/2 line. I also use the standard GM TPI style fuel filters as well.

I tuned a 57 chev some time ago with a 447 cid SBC with an old Accel DFI system on it. That engine had a fuel problem much like what one would call starvation. But his problem was that the fuel was being heated so much by the engine compartment that it was actually vapor locking. He had such a big pump in the tank that with every round trip of the return fuel it was picking up a little more engine compartment heat. The fancy stainless steel tank that was in the trunk of this car was so hot that if it was a hot tub I would hesitate to get in it. I replaced the pump with a bosch in tank pump, insulated the lines and he made some mods to the engine compartment to get more ventilation thought it and that cured his problem.

Then the other day I was tuning a friends 383 C4, it ran out of fuel at 3500 RPM. A new fuel filter temporaily cured that problem which reared its head again at 48000 RPM. Replacing the pump cured the problem all together. She revved to 6000+ with not a hint of any fuel issues. The AFR across board was well within my target of 12.5:1 beyond 4000 RPM.

 

I can imagine you're having trouble with a stock '82 fuel pump. The Crossfire that pump was built to feed, had a fuel system spec of 9 to 13 pounds of fuel pressure. Ordinarily, I'd say just go the a stock TPI or better yet, LTx fuel pump, but you're pumping out enough power to justify the Walbro. The pump should fit right into the stock location in the pump/sender unit, and you'll never hear it.

RACE ON!!!

 

Thank you very for all your prompt and insightful comments. I just ordered a Walbro pump a few minutes ago.

Ken
Albuquerque, NM