Explorer wont start

[phntmfoot]

I have a 95 explorer with a 4.0. Two days ago i went to start it and the motor turned over but it wouldnt crank. After trying it several times, it started. Over the last two days, it has become more and more of a persistant problem. The fuel pump kicks on (runs continuously though) and if i spray starting fluid in the intake, it will run until it burns that off. I've taken the line of past the fuel filter and get gas coming out so the filter is not clogged and the pump is working. I'm at a brick wall here.

 

[Donner]

Welcome! Have you examined the negative battery cable? That's seems to be a problem lately. How many miles on your vehicle?

 

[phntmfoot]

I installed a brand new battery this week. Doesnt seem like that would create a fuel issue. the fuel pump runs at all times if the key is on but it wont start unless i spray directly into the intake. after it burns that off, it shuts off again. i've taken the return line off and it has fuel pumping through it too. would the fact that i ran it really, really low on fuel the night before i had this problem contribute in any way? there are 140,000 mile on the truck.

 

[James909]

I'm a little confused when you say it turns over but won't crank. Do you mean that the starter is cranking the engine but the engine won't start? I'm assuming that this is what you mean. Since it starts on starter fluid you clearly have a fuel delivery problem. You should check the fuel pressure. Just because fuel is flowing doesn't mean that there is enough fuel pressure to start it.

 

[phntmfoot]

You're correct. thats what i mean. the starter turns the motor but the engine doesnt actually start.

 

[MrShorty]

I would second a check of the fuel pressure. Spec is 40 psi and an unscientific minumum is near 25 psi to get the engine to start. Pump may be running, but not generating enough pressure.

Other thought is something wrong with power supply to the PCM or something. The fuel pump shouldn't run continuously like that, which suggests something bigger is wrong. Can you pull codes from the computer? Are the injectors firing?

 

[Russ in CT]

Maybe the pump is running continuously because its trying to build sufficient pressure but can't. So this would second (third?) the notion that it may be getting gas, just not enough (pressure). Check the fuel pressure.

 

[budwich]

sounds like your regulator might have a problem. check to see if there is gas in the vacuum line. and as posted, a fuel pressure check will help.

 

[phntmfoot]

Replaced fuel pump.

I'm not sure i'm making myself very clear. I'm not a mechanic. I am just flat broke and cant afford to take my truck anywhere. The cheapest gauge i found to check pressure was $70 so I went ahead and sprung $20 dollars extra and bought the new fuel pump. I installed it and have the EXACT same problem. When I say i'm not a mechanic, some of your references are wasted on me because I blatantly dont know what you're talking about. In short, if someone could dumb it down in regards to regulators and things, i would greatly appreciate it. Thanks for any help you can give me.

 

[phntmfoot]

Are the injectors firing?

It would appear the injectors are firing because the truck starts on carb cleaner.

 

[phntmfoot]

wound anybody know what the small grey box with the 3 prong plug on the right side of the intake is for? sometimes when i mess with the wires to it, the fuel pump shuts off and it starts.

 

[Russ in CT]

Attempt to dumb down what everyone is telling you:

Your engine is Fuel Injected (as opposed to using a carburetor). therefore the fuel system consists of an electric pump, which I believe is located inside the fuel tank, the fuel lines that go from the tank/pump up to the front, the fuel filter, the fuel pressure regulator, the 'fuel rail' that is bascially a tube up at the engine intake, and the fuel injectors that pump the fuel into the motor. The injectors are connected to the fuel rail, the fuel rail is connected to the fuel pressure regulator, the fuel pressure regulator is connected to the fuel lines...

On the fuel rail there is a valve, with a screw on cap (probably blue), looks exactly like a tire valve. One easy way to tell if any fuel is actually even getting up to the injectors, is to take off the cap and 'let some air out' of this valve (just like you would let air out of a tire). Only guess what? It ain't gonna be air. Its gonna be gas, and its gonna want to spray in your eyes, so be real careful.

If there is gas, and if it squirts out real good, you at least know the fuel pump is working, and you have SOME fuel pressure. Is it enough fuel pressure? Ask somebody that bought a gauge.

If you don't have enough fuel pressure, then although the engine may start, and may even drive, it won't always have enough gas and the engine will stall or run bad. That could be caused by a bad fuel pump, or a bad fuel pressure regulator.

The fuel pump just pumps at a constant speed/volume, and its usually way more pressure then the fuel injectors want. So the fuel pressure regulator adjusts the pressure, bypassing the excess, to maintain a constant pressure at the fuel rail.

So if the fuel pressure regulator is bad, it might be bypassing too much, so not enough pressure at the injectors. Or the fuel pump might be bad, never supplying enough pressure for the regulator to do anything with (instead of bypassing, its letting all the pressure staright through, but its still never quite enough). Or it could be a clogged filter, pump can't push past it to get enough pressure at the regulator input.

Since you changed the pump, you know its not that, but you still don't even know if your problem is low fuel pressure or not. Need to verify that first.