OT: 95 Isuzu Rodeo dies, now won't start

We have a '95 Rodeo with a 3.2 liter engine that I can't figure the reason why it won't start.

The symptoms:
at first it would run for a while then it would just die as if the gas was cut off. We let it set for a few minutes then it started fine and we made it home. Next day, started right up, idled for maybe ten minutes then just died. Started it up again, ran for a couple minutes then started to die and I would goose up the RPM's, but after a short time it still died,and now it won't start at all. The fuel pump is working--I can hear it back by the tank and I can hear fuel flowing up at the engine. The fuel pump relay seems to be working okay and I replaced the in-line fuel filter encase it was restricting flow. Tried starter fluid sprayed into the air intake--no help.

Any help diagnosing the problem would be greatly appreciated.

You say it is not a gas issue---then think firing and/or vacuum. Have you gone through the "trouble shooting" section of your manual? The fuel pump was my first thought, also.

stuball48 said:

You say it is not a gas issue-

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It seems very much a gas issue, but everything I've looked at on the fuel supply seems okay. Haven't checked the pressure since I don't have a fuel pressure gauge, but I don't think that's the problem since I can't even to get it to catch with starter fluid.

Basic mechanics to begin with. Fire, fuel, air and timing. That's what makes an engine run or not run.

Is it getting fire? Pull a plug and lay it on the block so you can see. Crank engine and see if you have spark, if not, you have found the issue. If you have spark, you can then eliminate that possibility.

Fuel... The fuel pump can be running and even have some pressure, but not enough to properly fire the injectors. Your pressure regulator can be bypassing and not building pressure. The fuel filter can be totally stopped up and reducing pressure. Put a pressure guage on the fuel system and see what you get. No pressure, there's your problem. If pressure is good, on to timing.

Put the engine on TDC on cylinder #1. This can be confirmed with a compression guage, by holding your finger over the spark plug hole while hand cranking until compression is felt, or by removing the valve cover and watching for both valves to close on #1. Check to see if the distributor rotor is pointing to the plug wire terminal in the #1 position (if it has a distributor). If not, you have a broken or stripped timing belt. If you can get even part of the timing belt cover off, check for stripped teeth or a broken belt.

If all the above seem OK, you need to pull the codes on the engine. Girlfriend had a Dodge Neon that ran great... for 30 minutes, then would mis and quit. Let it sit and it'd run fine again for 30 mins. Codes said crank position sensor. $40 and a half hour of work later... and it ran perfectly.

It might have a fuel pressure sensor that triggers spark/engine computer.

Edit as posted up a bit.. A bad sensor in engine will do it too..

The electric fuel pumps gets intermittant.. Pressure is fine (until you remove pressure gauge) Runs then quits, won't start, sits a while, starts and runs long enough for a test drive, quits again...

I had more time than money a few years ago, and sat under my mothers car with a stethoscope on fuel pump... It would hum along fine for 15 minutes and then quit humming, engine died a few seconds later.... Datsun 510 (4 door with the Z engine..)

Pull the trouble codes, but check that pump first.

When it seems like it has no gas and quits, that probably is what the problem is..

Did this car (truck) sit for a long time, without being driven very much?

Low-Alloy said:

It seems very much a gas issue, but everything I've looked at on the fuel supply seems okay. Haven't checked the pressure since I don't have a fuel pressure gauge, but I don't think that's the problem since I can't even to get it to catch with starter fluid.

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If it's not kicking with starter fluid, I would look else where. Take a spark plug and lay it out where you can see it and see if it fires when cranking. Could be something in the ignition system starting to fail and or failing like the coil or crank sensor or maybe just a loose connection. Run a compression test to see if it's has or lost compression. Also check for a vacuum leaks.


Tom

I bet its a dumb computer chip that cost twice what the old beater is worth.

Im cool with cars that get high milage and run on almost no fuel but when the chip poops out and they want $700 IM very angry.

I see a big bill in your future..

Ditto what Tom said, you gave it fuel-no good. If you shot the starting fluid into the intake, so there's the fuel and air. Spark and compression are all that's left.

A fuel pressure sensor could be the problem-computer cutting spark off-but that is still a spark problem.

Some engines only have to have a problem with one cylinder to not work if the knock sensor/fuel sensor..etc are all in one cylinder. Hence if number 1 cylinder says no fuel needed, none is injected-to any-then you hear it returning to the tank.

Good luck.

P.S. The spark has to be when it is supposed to be.
That's what I love about Quadrajets and dual points.

This reminds me that in 1991, a friend had an Isuzu that ran low on engine coolant. He added water to it and made it to work. When he went to leave it wouldn't start. No spark. The engine has an antifreeze percentage calculator or sensor that wouldn't let it run.

Check to make sure yours doesn't have one of these, or like we did, drain some of the H2o out and add Prestone if your mix is weak.

Most safety switches don't kill the spark when there is no fuel, they kill the fuel if there is no spark signal for a given length of time (few seconds). Idea being the car has been in an accident and the fuel lines have ruptured and would be spraying fuel if pump isn't shut off.

Sounds like no fire to me, too, thus the reason that was the first check I listed. Usually quicker and easier than checking fuel pressure, as well.

Being an intermittent failure that went total, I'm guessing a Hall effect sensor of some kind (crank position, distributor position, or cam position), but not familiar enough with the particular engine to know which it has.

Does this engine have a distributor, any plug wires, how many coils. Pull a plug and see how it looks and smells.
Bill D.

Thanks everyone

Looks like a lot of testing for the problem is in my future.

For those that mentioned a possible computer problem; I don't think the Isuzu Rodeo has one--or at-least the Haynes manual doesn't show that it has. I hoping that it doesn't.

-I have an older 1987 Buick 4 banger that has had basically the same problem twice now---even tho it only has like 56,000 miles on it.

-first time I found the problem to be the crank sensor that bolted onto and into the side of the engine block.

-the two female receptacles of the crank sensor slid over narrow flat male blades that were attached to the internal crank trigger.

-these two female receptacles had relaxed to where they had right at zero grip or no compression against the male blades--therefore no signal to the dual coil pack assembly.

-the new sensor had something like at least .040" preload.
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-I replaced the sensor for about $25---but I measured the preload of the new sensor against the old sensor using pin gauges---and found the old sensor had opened up to where a pin gauge the exact same diameter as the male blades would not stay into the females if you let the pin gauge hang downward.
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-I took a little thin probe and worked the females back to where they had maximum preload---and kept that old sensor in case of some other failure.
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-less than ten years later I had the same problem---looked up my notes about what I had done the first time and decided to check and make sure that was the problem---and sure enough had the same exact problem.

-I re-installed the original repaired sensor, fixed the 2nd sensor and keep it now as the spare, and the car runs like it's supposed to.

If it doesn't have a computer, it should have a distributor, points, and a carb or manual injectors. The fact that GM has been in bed with Isuzu for a very long time, I believe it has some type of electronic ignition. The manual probably doesn't call it a computer. Maybe Electronic Control Module or the like. If it is in the distributor or on the side of it, that could be the problem. The GM HEI distributors were famous for causing the same problem you had/have. Especially in V8 full sized vans in West Texas. They would get so hot the white heat sinc lube would dry from between the module and the distributor floor. Ford put theirs on the outside, exposed to everything and they would start to run crappy or just quit.

I would pull a spark plug and ground it to the block with the plug wire on it and see if you have spark when it cranks. If not, go backward thru the fire system and you'll find the problem.

Low-Alloy said:

Looks like a lot of testing for the problem is in my future.

For those that mentioned a possible computer problem; I don't think the Isuzu Rodeo has one--or at-least the Haynes manual doesn't show that it has. I hoping that it doesn't.

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There is no such thing as a 95 model US market vehicle without a computer. It may be called by a confusing name, but it's there. Your Isuzu has one, and it most likely controls both the fuel and ignition systems. I don't have any of the details at hand, but I'm certain that the fuel and ignition systems are both electronically controlled.

The Isuzu Rodeo is the same as a Honda Passport of the same model year. If you can't find answers for one, search under the other name.

Honda has a long history of ignition module/ignitor failures. That's where I'd look first. Good luck.

If the OP is still following this thread - look at your alternator. I know it sounds funny but (some if not all) Isuzus of about that vintage have an additional alternator output that somehow interacts with the engine management and while the alt will test fine at the batt junction it can still have a lack of voltage at the secondary output. My suggestion is to have a look at your alt to familiarize yourself with the connections (locations & wire colors) and then let Google be your friend. My memory is a bit fuzzy on this but it seems as if the special output is connected to a green wire. I am on a Isuzu board where a number of members have gotten good deals on a non-running Isuzus. Once you find the output you could jumper it to see if you vehicle starts.

Check for spark at the coil wire, I suspect a bad coil wire. If no spark at coil wire, plug one of the plug wires in the coil and check again. Common ailment for this vintage, and it DOES have a computer.
Jim