Ok guys, I'm stuck on this fuel injection thing. I've got a '92 F150 with 5.0L and a 5 spd (Nite Edition if that helps). I've been chasing a problem for a couple of weeks now and am completely stuck. Truck has a clean idle and fires on all 8. When I drive, it hesitates real bad if I give it too much gas. If I really push it, it backfires. Engine still sounds like its running on all 8, but no power output, it seems to hold itself back. Seems to have most of its problems below 1700 rpm. Once I pass that, as long as I dont' give it too much gas, it runs fine, but I'm barely touching the gas pedal. I have already replaced the following...

02 sensor
spark plugs and wires
distributor cap and rotor
air filter
throttle position sensor
fuel pressure regulator
fuel filter
iginition module
and I punched a hole thru the baffles in a perfectly good catalytic converter

Runs better in colder weather.

I've already cleaned the Idle Air Controller and the throttle body. I don't think its the injectors cuz it wouldn't fire on all 8 then. Right?

No vacuum leaks, its getting fuel, air and spark. No "Check Engine" lights. Any ideas?

I've got plenty of experience on the carb models. Previously owned an 82 and an 86. Can't figure out fuel injection to save my life.

Another quickie, ignition timing...I've disconnected the spout connector, but I cannot find the gauge to check ignition timing. I know its supposed to be 10 degrees btc, but I can't find the timing marks. A little help if possible. Thanks.

 

Since you have replaced a lot of components and if your truck is equipped with IAC, I would suggest to try to clean the IAC and the IAC spot with a Throttle Body Cleaner. Or replace the IAC (Idle Air Control solenoid).

 

Well he said he already cleaned the Idle Air Controller and the throttle body. The gauge to check the timing is a little hard to spot, right above the harmonic damper, you may have to clean it a little and run a diagnostic

 

hey man maybe try fuel pressure test or a clogged cat converter

 

tried the cat already. that was kinda a last resort. ran a pole from the back of the cat all the way thru the baffels to the collector from the exhaust manifolds. should have at least helped, but it didn't.

fuel pressure should be good. i can hear the pump running, and i've replaced the fuel pressure regulator and the fuel filter. anyone ever hear of injectors causing something like this?

 

Just because the pump is running, does'nt meant it's putting out the correct pressure. You can have enough for the engine to run but not enough pressure for increased demands. The backfires is a good indication of this, being the engine is running to lean from the lack of fuel. "Check you fuel pressure." This is key factor for these engines to operate properly.

 

Have you checked the computer codes? One thing not to do with EFI is just throw new sensors/parts at it and hope it works (guesswork). That type of "diagnostic" work adds up real fast and uses up a lot of the time. I would check computer codes (if not done yet), the timing, fuel pressure, and go from there.

 

i've been waiting on a buddy of mine with a code reader. not throwing any "check engine" lights so it wasn't necessarily my main concern. started with whatever made sense. did as much troubleshooting as I could with my carbueration knowledge. i think i'm going to have to give up and let technology take its course.

 

Gotta check the codes, they don't necessarily throw a check engine light

 

Dont need reader to pull codes
http://www.dalidesign.com/hbook/eectest.html

Jump it to use check engine light to pull codes
http://www.off-road.com/ford/bigbron...ck.html#Jumper

 

hey why does this guy post for help if he not going to take any one's advise????

 

jason, so far, I've been told to check everything that i have already done (IAC, Cat Converter) and the fuel pressure. i was under the impression that the fuel pump would either run or not run. therefore, since it was running, i thought that it was working correctly. thanks to the advice I've gotten here, its another place for me to look.

i've been posting on the forum because I'm staring at a rainy weekend and can't really do too much on the truck. (driveway mechanic, no garage to work in). i was under the impression that FTE was a place for me to learn and discuss varying ideas on how to fix my truck. i'd love to jump out there right away and get working on this, but i don't think my boss would appreciate me calling out sick monday because i wanted to fix my truck. but, i thoroughly appreciate the critizism.

 

So no codes?

 

haven't yet, but its next on the list.

 

Have you cleaned the injectors yet? I didn't see that listed as tried.