Fuel Pump Pressure

Dreded · Post by **Dreded** » Thu May 05, 2005 2:52 pm

Can someone take a quick look in a shop manual and check to see what pressure the 1990 intank fuel pump puts out. I noticed there is no pump on the frame rail anymore in the '90.

DBrown · Post by **DBrown** » Thu May 05, 2005 8:17 pm

I can't remember the exact amount but I think it is only like 7-8psi. it is just a feeder pump to get fuel to the high pressure pump on the frame rail. that pump gives somewhere around 80-100psi.

I have herd of people running a carb off the feeder but I have never tried it myself.

Dreded · Post by **Dreded** » Thu May 05, 2005 9:29 pm

Not to be rude DBrown i appreciate the response but as I said THERE IS NO PUMP ON THE FRAME RAIL ON A '90 only an intank pump but thanx again for responding

DBrown · Post by **DBrown** » Fri May 06, 2005 5:36 am

lol, sorry man, I completely missed that......I would think that the in tank would be the same as the one on the rail. if it had the 2.9L it should be 80-100 to run the motor. the 4.0L is 85-100 I think. that is what autozone told me when I was doing the 4.0L swap. they never said anything about only one pump. they just said pressure at the rail would be that, then the regulator would knock it down to around 35psi. not sure about the 2.3L
again sorry......

Dreded · Post by **Dreded** » Fri May 06, 2005 8:44 am

no worries but using a regulator does it hurt the pump at all to knock it from 80 psi down to like 5-7? because none of the regulators have a return.

Exhauster · Post by **Exhauster** » Fri May 06, 2005 10:25 pm

the working pressure for the intank pump on an 89 & newer is 40ish lbs.... you can't use it with a carbed engine. if you choke it back that far it will overheat and burn up the motor in it. you could probably use an 86-88 intank feed pump for a carb.

Dreded · Post by **Dreded** » Sat May 07, 2005 2:02 am

In my '86 I was just using the feeder pump but it was noisy when pushing fuel that far. I was hoping to get a quiet solution.

DBrown · Post by **DBrown** » Sat May 07, 2005 5:15 am

in my 76 the guy that converted it over to elec fuel pump just used an off the shelf pump from autozone and it has worked well so far. I think he only paid like $20. it is not that bad. but he mounted it up at the engine and you can hear it but it is not too loud. I would mount it on the rail and it should be pretty quite. another thing to think about is it is easier to push liquid then it is to pull it so back at the tank is deffinatly the place to put it if you can.