Check Engine Light & Rev Counter drops out

[BigHorney]

Hi All,

I have a 1995 Isuzu Bighorn 3.1TD, Engine No. 4JG2

Check Engine light comes on intermittently when driving, even @ 100kmh and suffers an erratic Idle

With the Check Engine light the Rev Counter drops out altogether and the engine starts pulsing quite a lot (erratic Idle
) - so isn't happy about something, if I come to a stop it can stall due to the pulsing revs - erratic Idle

If I turn off the car and start it up again the Rev counter comes back and the Check Engine light dissappears - albiet only for a short time until it happens again.

Issue seems to have crept in since I had a slipping Alternator belt due to a broken Belt tensioner - I feel this could still be related to my issue and maybe needs even more tightening but maybe I'm wrong

Has had me baffled for some time.

[geeves]

is this the electronic or mechanical pump?

[BigHorney]

Not too sure on that one Jeeves, it's has a manual diesel pump located in the engine compartment if that's what you're referring too.

Or maybe you're referring to the cabling from Gearbox to Dashboard for speed/rev regulating.

This model is a 1995 3.1TD

I was trying to replicate the problem and was switching from 2WD to 4WD and then it happened whilst idling and rev counter drops out and the engine starts pulsing up & down by itself.

not sure if I have narrowed it down, I can only see a VSS Vehicle speed sensor underneath connected into the Gearbox, not sure what other gadgets are under there to check

[BigHorney]

Pretty much believe this is due to the slipping belts, but then again this has had me stumped so I don't have a clue really.

BTW I have since had the tensioner and belt fixed by mechanic so all is tight again, so that has ruled that out

Seems like the governor in the diesel pump may be the way to go so will find out what I can on that

[geeves]

My money is on the governor in the diesel pump. 95 could be manual or electronic. Have a look The manual has a cable on the front the electronic a box on the back and no throttle cable. Electronic pumps are known foe governor faults and this is the symptom

[BigHorney]

Thankyou for the reply geeves, much appreciate pointing me in the right direction as this is still happening and is very fustrating when Rev Counter drops out and Engine starts pulsing to the brink of cutting out at every set of traffic lights, so I must get to the bottom of it.

Will check out what I can find on the governor in the diesel pump or at least point my Mechanic in that direction.

Excuse my ignorance around Diesel pumps, but if the issue is with the governor which I reckon you are spot on with your diagnosis, would you happen to know what that would entail, a replacement pump (Ouch!) or a fix to the actuator/governor.

[geeves]

Its deep inside the pump so rebuild

[Myarmila24311]

Is this solved? Any update please... Same problem with my bighorn... hope not to point to that governor

[DonaldNZ]

if its electronic and if the alt belt Slipping, not charging, low voltage to ecu and pump might cause hickups,.

easy test is a voltmeter across the battery ~14v with the headlights on @ 2000 rpm, or take it for a drive with a fresh charged battery to see if any improvement., cheaper than a fresh pump

[Myarmila24311]

Yes, it is efi pump. The problem occur after wash the engine just with water only. Done spraying and cleaning every connector in engine, especially harness to efi pump. Seem ok but only last 3 days. Idle, power is ok. No smoke or less black smoke on hard acceleration. The hiccup is like ghost. Not permanently and not always. In common, it appear when on accelerate and yes, the alternator belt is a little lose. Meter in dash always show 13v to 14v. Will check that belt issue. Not seen and miss that. Very appreciate given an idea. Many thanks..

[Myarmila24311]

My theory, looks like current supply issue. When accelerate, electric governor in injection pump request more current to give more fuel. Maybe wiring or source power cant handle that current arise, then... Ecu trigger that hiccup. My 20 cent...

[DonaldNZ]

It could be a power failure, seems likely given you just washed it

I'd clean it first as best I could , If you lived in my town if you wanted I'd show you how I do my car in the local $2 car medium pressure wash on warm soap.

I keep my truck clean. I never power wash any connectors up close, so they stay original dirty
I go as hard as needed so I stay clean when checking the oil and clean enough to easily see damage or leaks loose hose clips and nothing is likely to contaminate the pump or loom connector on dis connecting

be super careful you don't bend anything, just looking for different or less gloss
I get new plastic bags , probably illegal now , and put over every connector as soon as I pull it off so its much harder for me to damage it with dirt


Id think about my static electricity content so I'm less likely to induce a mystery future intermittent problem reducing my bragging rights about how sweet my ride is.

I wear natural fibers, one good reason, usually less static generated,

you can buy for $5 anti static wrist straps. great idea and much easier

If I dont have one in a car, I'll pull my sock down and hold my ankle against the door stationary latch, after I've wiped it, so Im common with the car ground so less likely to be different due to static generated by my natural movement in my clothes. and moving across furnishings floor chairs. story goes going to the moon, brazillions was spent tracking down polystyrene cups and clear folders creating thousands of volts of static electricity destroying millions of dollars of equipment .

one training class I attended Ron claimed he tested the anti static crc or similar contact electronics cleaner beside the nozzle and it topped out and froze his static meter, which later recovered. I do not spray connectors connected to electronic devices.

spray it into a cup, touch cup and artist brush or cotton ear bud to frame of vehicle hold in hands and paint each terminal, maybe a cotton ear bud on bigger gear and you can get more grunt onto the cotton ear buds

initial clean might be with a grounded artist brush cotton ear bud and cleaning spirit { I use ipa or similar ] me holding it in each hand while lying on a plank beside the guard under the hood on a foam mat with my jumper lead on the the plank where I can touch it the other end and door latch or battery negative lead.

Id let it get well dry before disconnecting anything with excellent light, outside is best on a table or saw stool so you can photograph the connectors as close as possible , sometimes I'll use a small piece of mirror glass to get the good photo.

Id remove the pump connector and get my best torch and clean the lens on my camera phone and do the macro on each and every pin from both sides , then do the socket.

Migh come right with a wipe out with the cotton bud and ipa, keep an eye on your bud each cleaning spirit each dip between each terminal


if its faulty, pitted, burnt, eroded, less shiny, heat witness marks, change in colour,

layer of ~800 grit might be a do or die for the contact material, {it will remove the special surface layer so the terminal may now be more likely to corrode without attention] on both the pin and socket if needed, I wash it with meths and a fresh ear hole cotton bud or a clean tooth brush use a fresh piece of 800 each pin so less contamination, or wash the paper in like ipa / spirit / meths. then with 1200 paper until its quite nice, check for pin tension if required by testing each pin into a tube the same size as the socket by drilling a hole in say the end of a 6~8mm bolt and compare by feel in grip tension or how easily the pin slides, similar for a socket, I feel inside each socket with a clean drill bit [non cutting end] once its clean. id use a clean smooth drill bit

please confirm the following is correct failure sequence

car ok -> car have loose belt / alternator failure & single cold engine wash including the efi pump are and connector -> alternator fixed ok _> faulty engine run

then following this

one cold engine wash

then following this

spraying and cleaning every connector in engine, especially harness to efi pump. Seem ok but only last 3 days. Idle, power is ok. No smoke or less black smoke on hard acceleration. The hiccup is like ghost. Not permanently and not always.


If it continues maybe strapping a thin rubber flap over the connector that allows easy drainage

[Myarmila24311]

Thanks a lot for advice and guidance. Will do that this weekend. I want to take out all harness to that pump to examine but stuck at ckp@csp sensor(dont know what is the real name). Will update soon. Hope it will solved after do the deep cleaning in each connector.

[DonaldNZ]

I'd be as gentle as possible as older looks can be very brittle

[Myarmila24311]

Yes of course. One of connector(TPS sensor) at pump missing it lock already.

[DonaldNZ]

cable ties can be handy.

[Myarmila24311]

My Bighorn finally solved about this issue. After open the wiring loom, its have oil engine in it, mix with a little water. I think the current has jump over to interrupt the signal from sensor(crank sensor, tps sensor) and cause that light. After clean the wire, wrapped it again, then no more that hiccups. Each connector in injection pum is still clean. The lead are still shine like new.

[Myarmila24311]

Since the governor is a motor with permanent magnet. So there is a induction current espcially during accelerate. It will jump with help of oil and water. My two cent.

[DonaldNZ]

Well done fixing it