No power to fuel pump?

[yorktown1]

I have a '94 XLT that had intermittent starting problems last year. On an infrequent and random basis the engine would crank fine but doesn't catch. After wiggling the wires and tapping on the fuel tank it would start, but eventually I was told the fuel pump was failing. I knew it was 12 years old so I had it replaced and everything's OK for eight months, but now the same problem is occuring. When it's working, you can hear the whine of the fuel pump when the key is turned. When it's not, no whine so I don't think the fuel pump is getting power. Once the engine is running I've never had any problems, so I'm not sure it ever was a fuel pump problem. Sometimes it won't start, then after sitting for an hour it will. Any suggestions?

 

[sn0border88]

Look on auntozone.com for wiring diagrams and track down the fuel pump relay and check the wiring for it. Replace them and all associated fuses. Also check the termainal connections for corrosion, and for a bad ground.

 

[91n93explorer]

Did You Try The Fuel Cut-Off Switch Under The Dash? Mine Got Jarred Once And Disconnected.

 

[BrooklynBay]

Welcome to this forum! Your PCM controls the fuel pump, so if your PCM isn't getting power, your fuel pump won't either. Do you see a CEL when this problem happens? Check for bad ground connections.

 

[Brett F.]

Position #7 in your fuse block under the hood I believe is the fuel pump fuse. I want to say is a 20A .

 

[yorktown1]

Thanks for the inputs

Thanks for the info., I did check the fuel cut off switch under the dash, and it's OK. Also, no check engine light (assuming that's what CEL is), but I will check the PCM. I'm borrowing a shop manual from a friend so I can track down the fuel pump relay and wiring to replace and check for corrosion or bad grounding. I'll also check the fuse. Thanks again, I'll let you know how this works out...

 

[lqy125]

Did you change the fule pump relay? My 94 XLT (with 180K) had a problem to start right after the engin was off for 10 to 20 minutes, when the engin was cool, it can start again and runs fine. I traced to the fule pump relay and bought one from AutoZoe for $6.00 and have not have any problems since.

 

[theurge]

Did you change the fule pump relay? My 94 XLT (with 180K) had a problem to start right after the engin was off for 10 to 20 minutes, when the engin was cool, it can start again and runs fine. I traced to the fule pump relay and bought one from AutoZoe for $6.00 and have not have any problems since.

I agree - my bro's old gen 1 did the same thing. It would start up when it was cold, but when it got hot it wouldn't want to start again. Finally replaced the relay and he never had a problem again with it. That is until the trans started having shifting probs and we got rid of it.

 

[lars1367]

Here's more info than anyone should know on this subject:
Same here on my '92 Ranger STX. What happens is that the unused fuel is returned to the tank from the engine (but slightly hotter than when it left the tank). The resulting increased overall fuel temperature was causing the relay to trip a code. What caused this? Apparenlty the truck was showing it's age, but it became worse when I switched to 10% ethanol blend fuel and added heat to the tank to prevent freezing from the sub-zero temps in the Arctic tundra of Minnesota. The neoprene lines were reacting with the alchohol and corroding. It was an expensive weekend.

 

[wcraycroft]

My 95 Explorer would occasionally crank but not start. Occurred ONLY when engine was warm -- never on the first start of the day. After waiting anywhere from a few minutes to 2 hours, the engine would then start normally. Happened between once every few months and 2 - 3 times a week, and VERY intermittently. When I drove it to work and then it sat for several hours, it would always start. When I monitored the EEC-IV codes, it would always start, of course. Finally took it to a dealer I trust and left it for 2 days so they could try to repeat the problem. They finally got it to happen and determined that there was no fuel pump pressure when the engine was in this state. They replaced both the Fuel Pump Relay and the EEC Power Relay. After these replacements, they could no longer duplicate the problem. This was almost 4 weeks ago, and I have not experienced the problem. It could just be the odds, or the relays may have been intermittent. Since it is a cheap repair you can easily do yourself, replacing these two relays would be my recommendation as a starting point.

 

[yorktown1]

Problem is Fixed!

Ok, it was the EEC power relay. I bought a new relay for $7.00, popped it in and haven't had a problem since (five months). I also replaced the fuel pump relay for good measure.

THANK YOU!

 

[shamaal]

Thanks for the follow-up, I'll add it to the database.