94 XLT won't start

[chamomile]

1994 explorer-won't start

I have replaced the fuel pressure regulator and the fuel filter and still it won't start at times . Now it's to where the engine dies while driving down the road. I can hear the fuel pump engage when I turn the ingnition to ON?, but not completely all the way. The times that I don't hear the pump (buzzing sound) the primer?...
it won't start then. Do I need to replace the fuel pump or is something overlooked here? Also it seems that when the engine "cools down" or not, it will start.

 

[Rhett]

So you are saying the truck starts fine when it's cold, but not when it's hot? Make sure the O2 sensors are working properly for one. Regarding the fuel pump, is the fuel pump relay working all the time, or just some of the time? You can swap the abs relay and fuel relay (they're identical) at the relay box on the passenger side under the hood. Switch them for a few days. If your abs light comes on, the relay is probably going bad.
That's the poor man's way of testing those relays...

Check the vacuum connections on the upper intake manifold; check the vac connection on the throttle body; check vac connection on the fuel pressure regulator.
Is the air filter dirty?
Do a fuel pressure test and make sure that new fpr is working properly.

 

[chamomile]

I have replaced the fuel pressure regulator and the fuel filter and still it won't start at times . Now it's to where the engine dies while driving down the road. I can hear the fuel pump engage when I turn the ingnition to ON?, but not completely all the way. The times that I don't hear the pump (buzzing sound) the primer?...
it won't start then. Do I need to replace the fuel pump or is something overlooked here? Also it seems that when the engine "cools down" or not, it will start.

 

[DeRocha]

Check the fuel pressure

Did you check the fuel pressure at the shrader valve on the fuel rail? Replacing the fuel pump is kind of a minor pita. I change my a few years back when the shop and dealer both wanted around $450 with a 90 day waranty.

 

[chamomile]

Swapped fuel relay switch months ago with another like one (heater)
They appear to be the same except for the 4 numbers on the bottom R side of the switch. Does this matter?

The ABS light goes on when initially start the truck then goes out. States in the manuel is should do this.Fuel pressure reg was changed last month by a repair man. Also the fuel filter. The prob is that I don't hear the buzzing in the (back) the fuel filter when this prob of not starting occurs. It seems like an elec prob and not how much gas it's getting. The CAT sure needs replacing. I have put $500.00 into it already and just got the truck.

 

[daveg]

Have you placed a fuel gauge on the fuel rail to look at the fuel pressure when experiencing the problem?
-=daveg=-

 

[Rhett]

Originally posted by chamomile
Swapped fuel relay switch months ago with another like one (heater)
They appear to be the same except for the 4 numbers on the bottom R side of the switch. Does this matter?

I don't think it matters, BUT you never know it might. That's why I have always swapped the fuel pump relay with the abs relay--because they have exactly the same digits on the relay from the factory.

 

[Rhett]

Originally posted by chamomile
The ABS light goes on when initially start the truck then goes out. States in the manuel is should do this.Fuel pressure reg was changed last month by a repair man. Also the fuel filter. The prob is that I don't hear the buzzing in the (back) the fuel filter when this prob of not starting occurs. It seems like an elec prob and not how much gas it's getting. The CAT sure needs replacing. I have put $500.00 into it already and just got the truck.

If you know the FPR is properly installed, and there are no vac leaks anywhere....and the relays are good...and you sometimes can't hear the fuel pump when turning the key to accessory, then you may be right, one possibility is that you are looking at an electrical problem. Either in the ignition itself or in the connections to the fuel pump. But it could also be the fuel pump telling you it's about to quit completely.
Also check the fuel lines for kinks--although I have not seen this in Explorers/BroncoIIs it did happen to a 78 Honda my friend owned way back when. I'd say either electrical or bad fuel pump though.

 

[TPLYNCH]

Try cleaning the contacts/replacing the Fuel Pump relay in the black box under the hood.

 

[TPLYNCH]

Check your post in Under the Hood, and please do not double post in the future. You only need to post in one forum. Most people here read them all....

 

[Ray Lobato]

I moved and merged both threads.

 

[bnichols04]

yo man I had the same problem! All you have to do is go under the hood and take the fuel pump relay out and take it to the delearship and get a new one. When I went they had some in stock. Replace it and it should start right back up.