What happens when you jump start a good battery. I have been having trouble with my fuel pump and I notice when engine won't start, jump starting fires up the engine. I am getting the fuel pump thing fixed nest week. But is this practice damaging the battery or electrical components?

 

No,,,,won't causeany damage..

 

WOW, I'm sorry but that makes no sense. IMO if the battery is good then jumping it should have no affect on fuel pump. I think I would have battery load tested if I were you.

 

Thanks wheelsup and hayapower,

I have had this starting problem for over three months. Everything else has been ruled out, so it has to be fuel pump/fuel pump electrical.

This is what I have tested or replaced: battery, alternator/belt, spark plug cables ok, upper segment of battery cable replaced, fuel injectors cleaned, new fuel filter, pressure regulator ok, cap and rotor replaced 2004, solenoid ok starter is ok

I also had a mechanic do some troubleshooting and said it is the fuel pump. I also wondered why jumping the battery would start the engine. They said apparently it is "shocking" or giving a big jolt to the fuel pump.

I don't know about the computer.

 

Does it have this issue on 'every' start attempt? Or intermittent...

On a start attempt using only thevehicles battery,, 'Either' by cycling the key to the ON position or 'bumping' the starter with the key, you should hear the pump run for a few seconds as it builds system pressure.. Has anyone ever checked for spec.fuel pressure/volume during a failed start using only the vehicle battery? Thenjumped? Have you tried swapping the fuel pump relay with one of the others? I'd check for current leaving the inertia switch and/or at the tank connector prior to dropping the tank to verify a good/any pump voltage before a replacement...

 

Hello hayapower,

Let me answer your question. This starting problem is only intermittent. It started over three months ago. Earlier on, the problem would somtimes disappear for days or even weeks then re-appear. Now the problem seems to happen with more frequency. Maybe every 5 days I am guessing. So maybe a part is close to failing.

Like you said, I "cycle" the ignition and I hear the fuel system pressurize for a few seconds. When a no-start occurs, I hear no buzzing sound of the fuel pump energizing. Then I jump start and the engine fires up.

On Dec 23rd, I paid a mechanic $38 do some testing. Don't know how extensive testing was. I am almost positive he did some type of fuel pressure/volume test that you mentioned. By the way, the no-start condition was happening just prior to and during the mechanic's test. In fact, I think I remember him struggling to start the engine. He said "pump was not getting any pressure." and said I needed a fuel pump.

Now a couple other mechanics are not so sure it is the fuel pump. Like yourself, they think it might be wiring, electrical related, or the fuel pump relay.

No one has tried swapping out the relay yet. Are you talking about the one in the power distribution box (engine compartment), or isn't there another under the vehicle mounted on the outside of the fuel tank? What does it look like, and how do I access it?
Maybe I can save myself some money.

Anything else I should check?

Thanks,
Dave

 

Pretty easy way IMO to differentiate would b to try and spray some sort of brake cleaner in throttle body during no start issue and see if vehicle takes off and runs. If so then it is probably fuel pump, however it also sound a lot like potential relay/ ground issue to pump. Could be an expensive test with fuel pump.

 

Hayapower, read you latest response to my inquiry. Am I correct in assuming that both fuel pump replacement and fuel pump relay testing would involve removing the tank?

Is fuel pump relay in that tight spot between pickup bed and tank?

Thanks,
Dave

 

No,,

The fuel pump relay is in the Power Distributuion Box.. You can also run the fuel pump 'or test' for power distributuion and function/s to the fuel relay, inertia switch, and/or the tank connector/fuel pump, by jumping theData Link/Diagnostic Connector(STO) with the key in the ON position..Easily done as an 'elimination/step process' to diagnose circuit or component issues/failures or even intermittent problems as yours.. Insert a wire into the 'fuel pump' connection on the DLC connector and ground the other end.. With the key in the ON position the pump will or 'should' run continuously while jumped.. This doesn't by pass the fuel relay however, but takes the PCM KOEO 'timed run' out of the loop for an easier diagnosis, even more so if you happen to be having a 'current' pump run failure to pin point the cause.. You should also be able to hear the fuel relay 'click' on and off if the ground is 'interupted' by tapping it to the chassis rapidly.. With usually no more than a simple continuity test light, current/power flow through therelay to the inertia switch, down to the tank connector is done to verify no power drop outs 'before' the pump during an intermittent so not to replace a good working pump..

Here's a pic of the Data Link Connector/s STO/STI, and one for Power Distribution.. Only had a pic for 94 power box but should be similair...

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