Hot Fuel Delivery Problems

[St Ranger]

I have an 85 ranger with a 2.0 4 banger and whenever the temperature outside gets over around 80 degrees my truck sputters and hiccups when it warms up. if I pour water on the in line fuel pump (new) it runs good until it heats up again, this is the second new pump and the in tank pump is also new.
The truck runs fine on the highway in all temperatures but if i idle for any length of time it get worse and worse until it finally stops running, if i wait for it to cool down, it runs great. any help you guys can offer will be greatly appreciated.

 

[Earl43P]

Check power and ground at the fuel pump connector.

It is COMMON for the FP relay to fry its contacts and send <12v to the pump, resulting in heat. You should also verify the ground is good, using the resistance scale of your DVM.

 

[St Ranger]

i replaced the fp relay and the voltage / ground check good, this problem is compounded dramatically when the truck sits at idle for even short periods of time (red lights). ive changed both fp's done the pressure test of the fuel system and checked the pressure at the fuel rail all check good

 

[4b316]

Have you pulled the vacuum line off of the regulator to see if it made any difference?Is it a heat thing?Do it with the hood left open?Pull the pump on the frame rail and try just a high pressure in the tank and see if it makes a difference.

 

[4LO 4.O]

Sounds like a vapor lock problem, when the fuel heats up it causes condensation to form in the lines.

Is the fuel line near the manifolds or any other source of heat?

I use to have a truck that would run great until it got hot, then it would do as your describing. The line was a little short from where I had to cut it, ran a longer fuel line away from the heat sources and, problem solved.

Hope you get her back on the road.
Brian.

 

[St Ranger]

it acts like a heat thing but

The truck ran great for a long freakin time with the stock in line fuel pump (80,000 + miles) then I started to have this problem and because i have four rangers i just yanked the motor with the fewest miles on it (26,000) and slapped it in this chassis. I didnt do anything to the fuel lines / routing, i did replace the in tank (mid ship) fp and sender and the fuel pump relay. Truck ran great until the temp outside started to get above 80 then problem recurred so i replaced the in-line fp with a carter replacement, again truck ran good until it got hot out now it doesnt have to be hot outside all i have to do is sit at idle for more than 2 minutes and the thing hiccups and farts and belches until i let it cool down. The truck runs perfect at night never had the problem after dark so it must be heat and it stranded me about 75 miles from home a couple of months ago and i took my windshield squirter , cut the hose and directed it to spray on the fuel pump and limped it home by stopping at every watering hole between san juan capistrano and LA and refilling my reservoir. I've checked the ground on the frame rail mounted pump it checks out the relay is sending voltage to the pump, (this pump is noisier than the stocker) I can hear the pump running even when the truck hiccups and i hear it prime when i turn the key to on...this is killing me, it passed the california evap test and smog and when its runnin, it runs great but when it doesnt, it doesn't. HELP...If i didn't have so much into this heap I'd scrap it and buy new but between the custom interior/stereo/paint and the fact that I've got spare parts for days I can't part with the old girl. Any more suggestions will be appreciated. thanks to you who have chimed in already.