88 f150 4.9 straight 6 stalling when engine warm
Asked by bobo45 May 20, 2015 at 05:09 PM about the 1988 Ford F-150 XLT Standard Cab LB
Question type: Maintenance & Repair
I start the truck runs okay then when it gets warmed up the rpms start bouncing around give it gas to try to save it and it ends up sputtering out. fuel pumps are engaging already drained tank completely and filled with brand new gas and used STP fuel cleaner, PCV is not clogged, cant find any cracks in Vacuum lines, getting good pressure from tail pipe. sometimes it will be fine put it in gear to take off and it will sputter out have to do it quite a few times just to get it back into garage. I am completely stumped.
11 Answers
If the truck idles good, Then it is put into drive and given gas but wants to go dead. Sounds like the fuel pump. It should do this regardless of engine temperature. If it is hard to start after driving and the engine temperature is high, And you do not have this problem when the engine temperature is cold. Sounds like the engine timing could be set several degrees to high. If you think there could still be rust and grit in the gas tank that is causing this, Then put a inline a see through fuel filter in the gas line under the hood.
I have two 1985 F150 with the 300, 4.9. One needs a power brake booster and attempts to go dead when I have the vacuum line plug into the brake booster. When the vacuum line is stopped off it idles great, But then I do not have power brakes.
Check the idle air control, my truck had similar probs until I replaced the iac......
i got a 86 f150 302 auto. practically does the same thing but if the truck is moving enough to get air flow it runs great. if i start going slow and stopping more often in town the it will backfire, spit and sputter, die out completly then has to cool down(not all the time but most the time). i replaced the inline fuel pump and it does fine but it makes a wierd whining sould like its struggling thats when it starts running irratically. read alot about this but cant seem to find anyone who has fixed it.
SouldveNeverBoughtEF... answered 6 years ago
I've got the same problem, everything tests fine, I've even remotely the ignition module to the wheel well of the drivers side. Still, once it warms up it stops pulling and starts sputtering out until it dies. Crank it 30 min later it's like nothings wrong til you hit operating temperature again, then same vicious cycle.
I have an 88 Ford F-150 has a 4.9 6 cylinder in it you can come out here and Crank It Up when it's cold and it will run fine for about 10 minutes then it dies you get in there to crank it back up and it acts like it's out of gas sometimes you can turn the key on and off and then try to crank it it will start but then when you hit the gas it dies it has gas in it fuel pumps good everything checks out the way it's supposed to
If you figure it out let me know I am having the same problem with my 88 f150. I have replaced everything both fuel pumps and still no luck I am at my wit's end with this truck. I don't know what else it could be.
I have the same problem. Mine cranks fine and I can run about 20 miles if its not too hot outside and then it just stales out like it ran out of gas. If I wait about 5-10 mins it cranks off and then the cycle starts again. It's very frustrating. HELP!!
IT probably be the fuel tank control valve on frame mine was bad
I am looking to buy a 89 with the same issue, I think it is the fuel pump or some electrical issues. I will let you know. It is straight 6 also.
I have a 1987 ford f150 4.9l Inline 6 with the exact same issue. Anyone figure this out???
