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Fuel issue diagnosis


dodonne2
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I have a 1995 Pathfinder XE 3.0 V6, 4x4, 247,000 miles. I need help diagnosing a fuel issue, possibly electrical.

 

It has trouble starting, it wont crank at all, you turn the key and nothing happens, I have done this for over 20 minutes before it finally starts. Ive noticed if I turn the ignition on and let it sit for 5-10 seconds it starts usually right away (fuel pressure issue?).

 

When driving under acceleration it cuts out bad as though the ignition is being turned off for a half a second, it does it the worst in 5th gear at highway speeds, constantly cutting out as you drive. My brother has driven it this way for over a year and it has stayed the same for over a year.

 

We have already replaced all plugs, wires, distributor.

 

I've checked the fuel relay and that is not the problem.

 

Does this sound like the fuel pressure regulator or the fuel pump? Or possibly ignition issues ( ignition relay, starter relay)?

 

Anything helps.

 

Thanks,

 

Derek

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Trouble starting - Ok so if I were standing in front of your truck right now I would be first taking off the negative cable and wire brushing the terminal and battery terminal. Leave the cable off, then do the same with positive terminal. Resecure the positive side first, then the negative. Check voltage with multimeter. Should be 12-12.6. Now put key into ACC, the position just before the start position. Test battery again. Should read 11.8 anything lower than 11 volts is going to be struggling. Your starter needs at least 10 volts bare minimum to kick the engine over. So if this is the case, replace the battery. If you can manage to get the truck started then check the voltage when running. Should be 13.5-14.5. If it's less than 12.5 without any lights or fan on then the alternator is bad or not connected proper. Check wiring, wire brush under bolts so they are making clean contact with bare metal. This also goes fir your ground lead coming from negative terminal.

So if that is all good the next thing I'd check is the fuel filter in the fuel rail and replace it.

Another thing I did was replace every single blade fuse in the fuse compartment just for peace of mind.

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Can you make it cut out by wiggling stuff? +1 on checking the battery connections. If they check out, and the fuse links (U shaped wires hanging off the positive terminal) look alright, I would start it and try to make it cut out. Wiggle the key, wiggle the fuse links, whatever might be vibrating or shifting around while you're driving. I suspect something is loose/corroded in there.

 

Low fuel pressure will not stop the motor from cranking. It won't catch or run, but it'll turn over just fine. And running out of gas doesn't stop it dead in its tracks the way no spark does. That's what's got me thinking your issue is electrical rather than fuel delivery.

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Good info above, especially about checking the terminals and ground contact, and the electrical nature of the problem.

 

Do you see any corrosion on any of the contacts, fuses, relays under the hood or in the cab?

Have you checked the wires for the alternator, both contact and wire integrity?

 

B

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I will try to wiggle things to get it to cut out in the garage but it only cuts out under acceleration which is why I originally thought fuel. I was under the impression that low fuel pressure upon turning the ignition on may not allow the engine to crank. I will go through and change and check all fuses and grounding to double check and update you all tomorrow. Thank you.

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On acceleration, particularly hard acceleration, the engine twists a little on its mounts. Less if the mounts are good, quite a bit if one of the mounts is shot. That could be tugging on a weak connection and making it cut out when you put your foot down. If it was fuel starvation, I'd expect it to bog/cough/sputter instead of dying straight out.

 

And I know the starter doesn't care if there's fuel pressure because I ran my '95 out of gas at least once and it still cranked over like nothing was wrong.

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Trouble starting - Ok so if I were standing in front of your truck right now I would be first taking off the negative cable and wire brushing the terminal and battery terminal. Leave the cable off, then do the same with positive terminal. Resecure the positive side first, then the negative. Check voltage with multimeter. Should be 12-12.6. Now put key into ACC, the position just before the start position. Test battery again. Should read 11.8 anything lower than 11 volts is going to be struggling. Your starter needs at least 10 volts bare minimum to kick the engine over. So if this is the case, replace the battery. If you can manage to get the truck started then check the voltage when running. Should be 13.5-14.5. If it's less than 12.5 without any lights or fan on then the alternator is bad or not connected proper. Check wiring, wire brush under bolts so they are making clean contact with bare metal. This also goes fir your ground lead coming from negative terminal.

So if that is all good the next thing I'd check is the fuel filter in the fuel rail and replace it.

Another thing I did was replace every single blade fuse in the fuse compartment just for peace of mind.

 

 

^^^^^this and then......

 

No crank = no juice (or in extreme cases seized motor)

If battery and alty check out then you need to look at wiring to starter. It is an endless source of problems on these vehicles and many, many starters have been replaced when it was in fact a wiring issue. Easiest thing to do is attach wire to the starter solenoid that is long enough to reach the battery. Turn key on. Touch end of wire to (+) terminal. This by passes most all wiring and delivers 12 volts directly to starter and should crank starter if starter is good. (yes it will spark a bit but it won't kill you. I used this for years to start before discovering the relay mod) Use a rubber handled tool to hold the wire if you're worried). If starter cranks then search on forum for starter relay mod. If starter does not crank - you have a bad starter or wiring from ignition is faulty.

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Might also check the ignition switch itself. I had an S10 that had a similar problem and wouldnt crank all the time. Pull the shroud and wiggle the wires going into the ignition switch while you try to crank. Might be worth a shot.

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Update.

 

I checked all of the electrical connections starting from the battery down to the starter and I had plenty of power 14-14.5 going to the starter upon turning the key. I pulled apart the steering column and found that the ignition collar around the steering column had a little bit of wiggle room. Sure enough after tightening it up it starts right away everytime. It was the ignition! This also seemed to stop the constant cutting out while driving, although it still happens sometimes. I will keep everyone updated if I find out what the cutting out problem is, it sounds like I had multiple problems all coinciding together. Thanks for your help.

 

Derek

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