1990 Running Rough

busbo · Oct 24, 2004

I have a 1990 Bronco with a 351 EFI. After starting (which can be a little difficult) it wants to stall if you don't keep the RPM's up around 800-1400. It idles fine in Neutral, but stalls when you shift to Reverse or Drive. Does this sound like a fuel problem? Any suggestions? Thanks.

big timer · Oct 24, 2004

I have the same problem with mine, i just replaced my starter and cilinoid (or how ever you spell that god forsaken word) today in the driveway it was no easy task.
If someone answers your question could you please message me about how to fix mine too.

Thanks,
BiG TiMeR

hawk2100n · Oct 24, 2004

It sounds like a timing issue. A simple wiggleing of the distrubuter can solve this problem.

PS. it a solenoid

>-

busbo · Oct 24, 2004

o.k here's what i've done: distributor cap, rotor, wires and plugs are all new. I've checked and adjusted the timing...I think it's correct (it's hard to tell the way it's running). It seems to idle better in Neutral than anything but still wants to stall. Anyone got any ideas? Does it sound like an electrical problem or a fuel problem? Any help would be awesome. Thanks!

froggy47 · Oct 24, 2004

Idle Air Control Valve? Just giving you a guess

busbo · Oct 24, 2004

I haven't tried the Idle Air Control Valve. Would that cause it to want to stall when in gear? Also if you put it in Drive and hit the gas it's real hesitant, like it's not getting gas? Thanks for the help.

busbo · Oct 24, 2004

Also when idleing, the voltage gauge reads low...8-10 volts. The battery and altenator are also new. Thanks

froggy47 · Oct 25, 2004

If the volts are low on low idle, I think that could be normal, better to see what it reads when cruising. I'm not sure about the iacv, I have a 2.9 v6 & it was giving me starting & idle problems.

bluesman17 · Oct 25, 2004

Vacum leaks could cause it to idle poorly, it could be any number of things. My personal opinion is take it to a shop and have the codes pulled and tested.

BigNasty · Oct 25, 2004

Also when idleing, the voltage gauge reads low...8-10 volts. The battery and altenator are also new. Thanks

Where are you reading this?
It should be around 13-14.5 something volts if reading this on the battery while running. That is too low and can cause computer and other issues and all kinds of odd problems. Then again, the factory guage may be off a bit..
I would have the free battery/charging system check done at one of the chain parts stores to verify what the voltage truly is and go from there.
It is very possible that you got a bad alternator from the parts store or it has another issue, such as the voltage regulator.

busbo · Oct 25, 2004

I'm reading the voltage gauge in the dash, it reads 8-11v. I realize this may not be accurate, but it seems lower than usual. I have not checked to see if ALL pugs are firing but the wires are brand new.

EB Bronco · Oct 25, 2004

I think it's in the fuel system. I would replace the fuel filter. I do that once a year anyway on all my vehicles. I had the exact same problem you are having with a 1997 explorer with the 5.0. Check the evaporative canister. Mine had a crack in it and the only way I found out was to remove it from the fender and dunk it under water. When I saw bubbles I knew it was bad. I replaced it and it ran like a champ. That thing has a lot more vacuum on the fuel system than you would think.

Roger

busbo · Oct 25, 2004

Thanks for the info...i will try the canister...the fuel filter is new...thanks!

busbo · Oct 27, 2004

The canister seems fine. I hit the throttle body with some starting fluid and it started right up and ran o.k. for a few seconds but then wanted to stall. Does this sound like a fuel problem? The filter is new and the lines seem o.k. I have tried pulling the codes with the self-test jumper but it checks out system o.k. Any help is appreciated. hanks.

EB Bronco · Oct 28, 2004

I'm with Bluesman17 now. It sounds like a vacuum problem. I was thinking vacuum within the fuel system by suggesting to look at the canister, but now it could be a vacuum leak just about anywhere. I would check the codes.

Roger

busbo · Oct 28, 2004

I have tried checking the codes with the self-test conn., but it checks out o.k. I can't get it to run long enough or well enough to get it to the shop to get it checked. Any other ideas. Thanks. Man... this is killing me!

Guest · Oct 29, 2004

Do a test on the fuel pressure regulator.

busbo · Nov 2, 2004

I haven't tried the fuel pressure regulator. I replaced the TPS after testing it like the manual said (it checked out bad) but that did nothing. I'm running out of ideas. I still can't get the self-test to show any codes. It's really starting to piss me off. Am I outta line. Thanks :angry:

Guest · Nov 3, 2004

Try the TPS (throttle position sensor). It fixed my diyin at idle problem.

BK85

Phil · Nov 3, 2004

try a fuel pressure test if you have good pressure at the regulator it should be after that like an injector or some wiring have you looked at the air cleaner? my 89 was doing that and i hade a clogged air filter give it a try B)