94 explorer 4wd not starting sometimes.

[carlosvantega]

When I start the explorer it comes on but very weak starts to shake and shuts off. Sometimes has a rough time idling. Hasnt shut off while driving. What could be causing this to happen? sometimes it will start right up woth no problems but when it starts weak and I press the gas pedal it doesn't rev up. Its kinda like its fighting to get gas. Any help appreciated

 

[MrShorty]

For something that acts "like its fighting to get gas", I would probably suggest starting with a fuel pressure test. I believe a fuel pressure testing kit can be "borrowed" (with a suitable deposit) from places like Autozone. Because the problem seems intermittent, you may need to keep the fuel pressure kit on hand and ready to test when it has trouble starting (one of the irritating things about intermittent problems). If the fuel pressure test comes back normal, then you can move on to other possibilities. If the fuel pressure test indicates a problem, then we can pursue this diagnostic path.

 

[larrydd999]

I can think of quite a few things that it could be. If possible, try to check for any trouble codes from the engine management computer. There are instructions on this site on doing so without purchasing an LCD-based unit (but I did because I have 4 vehicles that can use it). In fact, it's the top subject on the 'sticky' list.

 

[carlosvantega]

I have figured out that if I hold the gas pedal down and start the car while doing so it starts up. Not perfectly, I have to continue holding it down for about 10 seconds after but it does start

 

[Wolfie_85]

Definitely a fuel issue. I would fuel pressure test it. Commonly, it could be a fuel filter, fuel pump relay (this is what fixed mine), or fuel pump. If it was fuel injectors, I would think it would be more consistent.

 

[MrShorty]

I have figured out that if I hold the gas pedal down and start the car while doing so it starts up. Not perfectly, I have to continue holding it down for about 10 seconds after but it does start

This suggests another path to pursue. One failure mode of the fuel pressure regulator is to develop a leak into the intake. This causes the engine to "flood" on warm starts. Does the starting issue seem more prevalent on warm starts?

Easy to check--after running the engine or attempting to start, disconnect the vacuum line to the FPR. If there is gasoline in this vacuum line, the FPR is bad and needs to be replaced.

 

[carlosvantega]

Just took it to O'Reillys got the codes Dtc 542, 181, 186, 189 I googled them but I don't understand half of the stuff people are saying about them online. Any ideas?

 

[carlosvantega]

Ok so I have this info 542 Fuel pump circuit open, EEC processor to motor ground.

181 Fuel system at part throttle rich adaptive limit, system lean (Rear Side).

186 Closed loop injector pulse width longer than expected.

189 Fuel system at part throttle rich adaptive limit, system lean (Front Side).

Where do I go from here?

 

[natenkiki2004]

When you turn the key on, do you hear the fuel pump come on? Does it shut off?

 

[vq5speed]

You could have a multiple things going on. First I would check all vacuum lines make sure there are no vacuum leaks. Vacuum leaks would keep it from idling.

 

[MrShorty]

Did your guy at O'Reilly's indicate if the codes (in particular the 542) was KOEO or CM code? The O2 sensor codes (the CM 18x codes) will probably not have much to do with a no start. But the 542 code indicates some kind of fault in the fuel pump circuit -- which can definitely be part of a no start. KOEO 542 indicates a fault in the fuel pump circuit present at the time the KOEO test was performed, a CM 542 (without an accompanying KOEO 542) suggests an intermittent fault in the fuel pump circuit.

If the tech at O'Reilly's did not know to distinguish KOEO/CM codes, I would suggest you learn how to pull codes yourself at home. We have several threads with instructions here, including my notes on pulling EEC-IV codes in the EEC-IV subforum.

Because of the 542 code, I would pull out a wiring diagram and a voltmeter and start testing the fuel pump circuit. It is a fairly simple DC circuit, so it should not be overly difficult to test (unless the fault is intermittent).

 

[coco944x4s]

Try switching the key on and off 5 or 6 times without trying to crank the engine. Leave about 5-10 seconds between each key cycle, and leave the key on 10-15 seconds each time before turning it off. After that, try to crank it. If it starts easily, fuel pump is weak.

 

[carlosvantega]

Mr shorty. He said the 542 code came up twice does that mean it came up as both?

 

[MrShorty]

The O'Reilly guy could not say? How was he reading the codes -- a special reader, or a jumper wire?

As noted in our instructions here, the EEC-IV system will repeat each set of codes. So it outputs the KOEO codes, repeats the KOEO codes, then outputs the CM codes, then repeats the CM codes. A lot depends on what your O'Reilly tech means -- were there 4 instances of the 542 code or 2 -- and would he know what to look for.

 

[Roadrunner777]

Not our Orielly's guy.