Low fuel pressure?

Topic: Low fuel pressure? (Read 2465 times) previous topic - next topic

Low fuel pressure?

December 27, 2005, 01:12:15 AM

Since I rebuilt my 302 it's been running rough at low rpm. In fact to even make it driveable I need to idle it at like 800 rpm. I've been checking things across the board for a while now and I'm really starting to wonder if the stock fuel pump is up for the mods I made. First a little background: 83 Thunderbird that came stock with a 2 BL carb and mechanical fuel pump. During the rebuild I gave it E7 heads and a non-roller HO cam. Though it doesn't exactly parallel the HO conversion article on Coolcats, I'm mulling over the article's warning that a larger capacity pump may be required. So tomorrow I thought I might pick up a pump for a thirstier 302, maybe an F150 same year? Any thoughts?

Low fuel pressure?

Reply #1 – December 27, 2005, 01:30:14 AM

ok what were you smoking when you thought the stock fuel system was up for those mods? cuz whatever it was send it my way lol. but i know its an area overlooked. but i would think a fuel pump off of a 351 would solve those issues. and since its the same block i belive it should swap out.

Low fuel pressure?

Reply #2 – December 27, 2005, 01:35:03 AM

Lol. Touche. Well I know the 351 is similar but are you sure the pump is compatible? I guess I can compare them in store.

Low fuel pressure?

Reply #3 – December 27, 2005, 01:37:26 AM

it should be cuz last time i knew the 351 eas based off the 302 block.

Low fuel pressure?

Reply #4 – December 27, 2005, 01:46:25 AM

Well according to car-part.com the fuel pump from a 1982 F150 with a 351W is cross-compatible with the 302. Though the electric pumps are mixed in there too. As far as I know my car has no in-tank pump. I'll check it out tomorrow.

Low fuel pressure?

Reply #5 – December 27, 2005, 01:57:00 AM

if its carbed i wouldn't think there would be one. was the stock pump mounted on the engine?

Low fuel pressure?

Reply #6 – December 27, 2005, 01:59:33 AM

Yep. On the timing cover.

Low fuel pressure?

Reply #7 – December 27, 2005, 02:06:43 AM

then that should be the only one. cuz i know on my cfi engine i have a high and low pressure pump. one in the tank and the other one next to the fuel filter. the one in the tank pressurizes the system and the one next to the fuel filter taks over after the engine is started. werd set up i know but if i did go with carbed i could just grownd the tan wie in the kick panel and use that low pfressure pump at all times for the carb.

Low fuel pressure?

Reply #8 – December 27, 2005, 02:18:27 AM

Sweet :D No worries then.

Low fuel pressure?

Reply #9 – December 27, 2005, 02:21:11 AM

nope none. i have all the worrys cuz id have to possibly upgrade my stock system for the sefi system or find a way to make what i have work with true sefi. more tunability and more power:evilgrin:

Low fuel pressure?

Reply #10 – December 27, 2005, 08:19:36 AM

my thunderbird is using a holley blue electric fuel pump with an adjustable regulator for my 4 bbl. 306 c-4 project car. no problems at all.....

Low fuel pressure?

Reply #11 – December 27, 2005, 12:01:21 PM

Yeah I considered buying an electric pump but they're pretty expensive compared to a simple mechanical piece. But I'm gearing up to put a big 4bbl on there in the future so maybe then.

Low fuel pressure?

Reply #12 – December 27, 2005, 12:02:26 PM

Quote from: sum_weirdo

Since I rebuilt my 302 it's been running rough at low rpm. In fact to even make it driveable I need to idle it at like 800 rpm. I've been checking things across the board for a while now and I'm really starting to wonder if the stock fuel pump is up for the mods I made. Any thoughts?

If it runs OK on the road, the pump ain't likely your problem...

Whats the specs on that cam again???

Low fuel pressure?

Reply #13 – December 27, 2005, 12:45:11 PM

The site is down. It does run good at higher rpms but given the nature of mechanical pumps that isn't surprising. The faster the engine turns the faster the pump will flow.

Low fuel pressure?

Reply #14 – December 27, 2005, 01:25:06 PM

Quote from: sum_weirdo

The site is down. It does run good at higher rpms but given the nature of mechanical pumps that isn't surprising. The faster the engine turns the faster the pump will flow.

True, but it ain't gonna cause a rough idle problem... If you had lack of fuel at idle it would be OK for a few seconds after the engine is revved, then start to idle poorly. Plus it would probably have a flat spot off idle... A pump won't hurt especially if it is old, but you'll still be lookin' for your problem...