Fuel Pump Issues on My 2002 Explorer?

[Andy1416]

Hello All, I updated the thread:

My truck died recently and after thorough testing it was deemed my fuel pump died. I had my mechanic install a new fuel pump assembly and fuel filter at the same time. But for some reason now it's hard to start. When I turned the key to the "on" position, and let the fuel pump prime itself a few times, it starts fine. The truck is my daily driver and the fuel isn't old. The spark plugs, spark plug wires, and coil pack are fine, I've had them replaced a few months ago, I replaced the battery at the same time too. Any help would be great, thanks.

 

[warnerwh]

When you say "it's hard to crank over and start" are you saying the starter cranks the engine slowly? If that's the case it would be your battery or possibly your alternator isn't charging it properly. You need to be specific please when describing the " hard to crank and start". If the engine is cranking at full speed like with a healthy battery and the engine takes a long time to start it could be a number of other reasons.

 

[Andy1416]

When you say "it's hard to crank over and start" are you saying the starter cranks the engine slowly? If that's the case it would be your battery or possibly your alternator isn't charging it properly. You need to be specific please when describing the " hard to crank and start". If the engine is cranking at full speed like with a healthy battery and the engine takes a long time to start it could be a number of other reasons.

My battery and alternator are fine. It takes a bit for it to start. But it helps when I let the fuel pump prime beforehand.

 

[warnerwh]

Are plugs and coils healthy?

 

[J_C]

Turn the key to the run (not start) position. Immediately/concurrently measure fuel pressure at the fuel rail. If you can get it running, measure fuel pressure then too. Best guess is it should be about 60+ PSI but I'm sure that info is several places in this 3rd gen subforum. Many auto parts chain stores have a loaner fuel gauge you can borrow with a deposit on it.

Then there is the question of how competent the mechanic is. What specific evidence led to the bad fuel pump diagnosis? Have you reported this problem to the mechanic and s/he can't solve it? Was a low quality generic fuel pump used? I don't trust the generic brands. Was only the pump replaced, or also the sending unit in the tank which presumably has the pressure regulator on it? Did the mechanic mess with anything under the hood, besides disconnecting the battery? I mean sure s/he might have measured the fuel pressure, but anything more intrusive than that, which might've damaged a wire, left a connector unplugged, or popped a vac line off?

Once it starts, does it run properly, not just idling but driving? Hook up a code scanner to look for OBD2 codes and if none are found, try a scanner capable of live data and look at things like the crankshaft position sensor while cranking, or if it gets started, look at temp sensor values and long term fuel trim, and of course fuel pressure if there's a value for that.

When you stated it died recently, how long has it been sitting with old fuel? Is it possible it's just gone bad, especially if there's ethanol in it? Have you tried having a helper crank the engine while you spray starter fluid in the intake?

I may be away from the forum for a few days but the answers to the above questions may help someone get a better idea of what's going on.