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Hook
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Registered: 3-13-2004
Location: Sonora
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When anything is intermittent without unusual external environmental conditions, I always suspect an electric/electronic problem first. this is
different than the lagging acceleration you mentioned at first. Mechanical things fail and stay failed.
Replace cheaper things first.
Dont know why a problematic fuel pump would only manifest itself on a specific cylinder. A cylinder misfire is probably electrical/electronic.
Is swapping the sparkplug wire from one of the other cylinders possible, to see if the problem moves to a different cylinder? Changing sparkplug wires
isn't as easy as it used to be.
Know anyone REALLY WELL with the same engine that will allow you to swap out a few things to try and eliminate things without actually having to buy
parts? Fuel pump? Wires to and from the distributor?
Let's hope it's not a Power Control Module or the module that controls the fuel injection circuit, if you have one. They are probably expensive and
probably only available from the dealer. Replace other things first.
Someone mentioned a known issue with the sparkplugs stripping out their threaded bases. I always assumed that solid contact with their threaded bases
is how sparkplugs achieve "ground" in order for the spark to cross the gap when electricity is supplied to the electrode. Can you get at that
sparkplug with your fingers and wiggle it and see if you feel a looseness in how it is mounted? Maybe there are times when it isnt achieving "good
ground" due to it's threaded mount being compromised.
On my Ford diesel, there was a known issue where an injector wiring harness (mounted to a valve cover) became loose after years of heating up and
cooling down. See if you can trace any wiring harnesses that send signals to individual cylinders. Maybe there is a wiring junction/plug that has
become loose or compromised.
I dont know much about your engine. Diesels are direct injection into each cylinder. Gas engines may be a single throttle body injector.
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SFandH
Elite Nomad
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each cylinder has an injector and coil on top of the plug
swapping plug wires to see if the miss moves with the wire sounds like an easy thing to do.
thanks, i'll try that first
[Edited on 7-20-2016 by SFandH]
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Bob and Susan
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Location: Mulege BCS on the BAY
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my engine is EXACTALY the same as yours...
the missing like you experienced was the fuel pump in the gas tank
the rough idle was the idle sensor thing
when the tank was full of gas it didn't vent well and idrilled a hole in the gas cap...worked too
when the pump finally died I hit a bump and it was gone
like a lightbulb
end the pain and replace the fuel pump
today my 2 year old battery died at the Pemex station...the operators at the Pemex called my mechanic...the brought a battery and fixed the
cables...great service...truck runs like new again...we checked the battery at the shop and it truly died...alternator fine...new cars are just better
because they haven't worn out yet
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KaceyJ
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That reminds me Bob, Low voltage can cause a problem in itself ,.
Not enough juice to run all the sensors and control systems.
I agree on the fuel pump
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Hook
Elite Nomad
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Low voltage isnt likely to cause a problem while you are at speed, unless you're alternator is shot. Your standard 90+ amp alternator will more than
make up for a bad battery while running.
This assumes that you are NOT getting too much resistance from your battery leads or somewhere else. BE VERY SURE THEY ARE THOROUGHLY CLEANED AND
TIGHTENED! They can pass voltage but sometimes not enough current (amperage) if there is corrosion preventing it.
OK, lets consider the fuel pump as a possibility, since so many are demanding it.
Since you are injected, you likely have a fuel pump that brings the pressure up to what the injectors need. The pump in the tank is not that, usually;
the tank pump is considered a primary"lift" pump (low pressure pump) to simply get the fuel out of the tank to a secondary (high pressure) pump.
CHECK THE SECONDARY PUMP FIRST, before you decide to drop your own fuel tank or pay someone the money to do it. It's often mounted along the "rail"
(inside your chassis member that runs front to back where the fuel line runs). While the vehicle is running take voltmeter readings at it's
connections to make sure it is getting voltage within 0.1-0.2 volts of what you are reading at the battery. Check for corrosion at it's leads.
Certainly the reading should be well above 13 volts while the engine is running.
If voltage appears normal, get a price on replacing that and see if it is reasonable enough to justify it. You should be able to find a replacement
outside of the dealer network. Check a Napa auto parts store. They seem to carry more non-Chinese replacements than all the others. I'm not a gung-ho,
buy American first guy; I've just experienced too much Chinese junk.
But DO THE SPARKPLUG THING FIRST! It costs nothing but time.
Usually, when a lift pump is failing, you will experience problems when climbing hills. The incline forces the lift pump to lift fuel higher and it
starves the secondary pump. Have you noticed that the problem occurs on inclines?
To Bob: yeah, it really sucks how short battery life is down here. I installed brand new Interstate batteries in my truck when I moved down here. They
were six year guarantee batteries and only lasted about 2.5 years. The heat just cooks them. Of course, I was not going to drive them back up for my
warranty claim.
So, I buy the best LTH or the best Duralast batteries at the Mex Auto Zone and hope I get three years. I am buying new ones next week, before I go
NOB. I have an idea that raising my hood at the end of the day and venting all that built up heat may extend their life. Just a hunch. Plus the
gassing in all that heat has me constantly fighting corrosion on the battery leads. Even a combination of those "wool" pads around the terminals and
the anti-corrosion spray is not 100% effective.
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Bob and Susan
Elite Nomad
Posts: 8813
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Quote: Originally posted by KaceyJ  | That reminds me Bob, Low voltage can cause a problem in itself ,.
Not enough juice to run all the sensors and control systems.
I agree on the fuel pump |
that's exactly right...
the battery cables at the battery corrode ALOT
i'm always fighting them
vasiine seems to work the best but once cleaned they never stop corroding
the lower voltage would flip a code and the engine light will come on if they are dirty...
I imagine the current to the pump is lowered too and the lower current could be "frying" it...remember lower current higher amps (heat)
there is only one pump hook...these are not diesels or fancy race trucks
forget taking the time with the spark plugs...new plugs HAVE to last 5ok miles by law...they last much longer
when you replace the pump replace the filter too...you may need to bleed the system the first couple miles to clear out the "air bubbles" you let in
when you opened the lines
my truck runs 5 days a week pulling a 5000 pound trailer...its has to run good or i'm screwed...its a work horse I don't have to wash...for sure not
the best truck I've owned but up there
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SFandH
Elite Nomad
Posts: 7084
Registered: 8-5-2011
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Bob, hook and others,
I appreciate the replies and the discussion. The gas tank is low and I was going to fill it but decided not to in case it needs to be dropped to
change the pump.
[Edited on 7-20-2016 by SFandH]
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Hook
Elite Nomad
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I have learned so much from discussion boards that are specific to my vehicle. Have you found a good board that discusses problems with that engine
and/or vehicle? It's better than a Baja board.
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Don Jorge
Senior Nomad
Posts: 646
Registered: 8-29-2003
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| Quote: Originally posted by SFandH |
Hmmm, do you have some reasoning behind that conclusion.
Call me crazy but I'm thinking a cylinder #4 misfire probably has something to do with the gizmos, widgets, and gadgets associated with cylinder #4.
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We have a few of those engines in delivery vans. I would put a new coil, boot/wire and spark plug in the #4 slot. They are notorious for failing
eventually and especially if you wash down the engines. We have had several failures over the years like the one you describe and changing out the
coil assembly and plug has worked. The fact it is kicking out a code specific to #4 is a there's your sign moment.
Of course the #4 on a pickup truck is a real beetch to get to. If you have not already done it think about changing em all out. You have some mileage
under the hood.
�And it never failed that during the dry years the people forgot about the rich years, and during the wet years they lost all memory of the dry
years. It was always that way.�― John Steinbeck
"All models are wrong, but some are useful." George E.P. Box
"Nature bats last." Doug "Hayduke" Peac-ck
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SFandH
Elite Nomad
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Yes, I've been reading several message boards. But I haven't found much about intermittent misfires on a single cylinder. One interesting development
is the Lucas fuel treatment did change the misfire from real easy to reproduce, 1500 - 1800 rpm, high gear, light acceleration to not so easy to
reproduce. Could be coincidence. Like I said yesterday I couldn't get it to misfire for 30 miles or so on the freeway, playing with the gas petal to
get different rpm/gear combos, but then all of a sudden it stumbled badly for 5 minutes at different loads and then smoothed out.
I've also erased the diagnostic codes once, P0304 came back and the check engine light came back on.
I know I could just take it to a shop and probably get it quickly fixed but since I drive a lot in baja it's good for me to know how these things
work. Plus I'm in no hurry.
I bet it has something to do with the air, fuel, or ignition. 
Right now I'd bet on the coil, agreeing with Don Jorge and his experience. If so, I'll need to decide whether to change just #4 or all 8 of them,
about $40 each. Significant for my thin, retired wallet.
[Edited on 7-20-2016 by SFandH]
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BajaBreak
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The stripped spark plug threads in the head issue I mentioned was on a friends 5.4L Triton, but I believe it was a '98? He told me they literally only
have 3 threads holding them in. I just now read you have an '03, and am not sure if it was changed by then.
I'd be careful removing the coils, and when re-torqueing them. Avoid yanking them side to side, just try to twist and pull. I'll try asking what his
symptoms were, but I recall he just said it runs like crap 
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woody with a view
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Change out #4 and buy a spare just in case. I carry one with me on every trip SOB. Now that I do it will never be needed.
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