Hey guys, occasionally when I switch the key to the "on" position my fuel pump does not turn on. and the truck will not start. I then switch the key on and off for appr. 5 times and then I hear the pump come on and then the truck starts right up and it runs perfect for however long I drive it. I changed out the relay, fuel filter changed regularly and all maintenance up to date. This has been happening for about 6 months and I have made some 200 mile trips and not 1 hickkup from the fuel pump when running hard. This fuel pump problem only happens at the key when the engine is not running. Every thing else is working properly when the key is turned on so I doubt it is the ignition switch. This is one weird problem
PS fuel pressure is at zero when the pump does not come on and it gets full pressure when I hear it run. Thanks Mike

 

I had similiar symptoms when my fuel pump was failing. I replaced the pump and haven't had a problem since ...

 

I've seen fuel pumps fail slowly, but this one is taking it's sweet time.

 

It happened again today. I kept turning the key to the "ON" position 10-12 times until I heard the fuel pump come on then I cranked the engine and it fired right up and ran great. If I do not hear the pump running and I crank her over she will not start. The weird thing is that once its running I get no stumbling or fuel pump issues at all. I would think that if the fuel pump was going bad, I would get some issues, ie running down the freeway at 70 mph or on hard acceleration, but my engine runs fantastic. It is only with this key-on situation that my fuel pump is erratic. Are there any know issues with the ignition switch on these `99 models. I searched this forum extensively but no luck. Thanks Mike

 

Does the theft light flash when it happens?

 

It goes out after 3 seconds, so its operating normal.

 

sounds like the pump is sticking at first, but eventually will start pumping. That is very typical, and putting electricity to the pump when it is sticking is hard on the fuel pump. Your keen ear may be extending the life of this one.

 

Thanks for the comeback. I think that the next time this happens I will supply an external 12 volts to the pump and if it still does not work then I know I have a bad pump.

 

This will be interesting - I vote for the ignition switch. Please let us know what you find.

 

Since everybody is guessing I'll throw in my thoughts. The plug on the firewall has got corrosion in it and until it is cleaned, yer gonna have issues with it.

 

OK guys, I removed the plug from the fuel pump cut-off switch and ran 12 volts to the pink wire and the fuel pump turned on. This was done when the key-on position did not turn on the fuel pump. Hey Labnerd, where is the plug at the firewall? And thanks for the help, this may be the problem Mike

 

I vote for an intermittent Fuel Pump. When you turn the key on and you do not hear the pump start, five the fuel take a rap on the bottom to see if the pump takes off. If it does, replace the fuel pump.....

 

sounds like a fuel pump on its way out as others have said. do yourself a solid and replace it now before it leave you stranded somewhere. had one go on me in SC while on vacation suddenly and it cost me 700 bucks and several gray hairs to get it taken care of.

 

see what fuel pressures you have while driving

also check the pump ground wire that goes to the frame for corrosion or breakage

 

Good point! Would it be just as easy to measure if there is 12 volts at the pump when this happens next?