Truck won't rev

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Skropeling
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Truck won't rev

Postby Skropeling » Thu Aug 23, 2018 8:45 pm

I have this strange issue happening right now. When I give my Pup more throttle, it just shoots out black smoke rather than increasing the RPMs. My mechanic says that the injector pump went out, and that the engines in those trucks die pretty quickly anyways, so he just suggests scrapping the truck for 100 bucks. I don't want to do that, just because of the gas mileage, small size, and versatility that comes with that Pup. I have a different theory about the truck, but I don't really know where to go with it. When I was changing my head gasket (which is what somehow triggered this issue) I discovered this thick, oily paste that was in the head and in the intake manifold. I'm pretty sure this paste is the result of oil from the crank case vent and soot from the engine somehow combining. I tried to clean it out, and I did get a lot of it, but I'm thinking that I may be pushed some of that paste further into the engine, possibly clogging the valves and restricting airflow, which would explain all the smoke I'm getting. I'm thinking maybe I can have a friend tow the Pup and I'll let the clutch out. Maybe forcing the engine to go to 3000-4000 RPMs (right now it won't even rev up to 1000) will force whatever's clogging up the engine out of the exhaust. I could also just take apart the head and clean everything, which would for sure be the better thing to do, but if there's a quicker way, I would rather go with that at the time because that Pup is my daily driver and only vehicle. Thanks for any help.

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JoeIsuzu
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Re: Truck won't rev

Postby JoeIsuzu » Thu Aug 23, 2018 9:32 pm

What year is your P'up? Does it have a draft tube, or does the crankcase vent into the manifold? Actually, I have doubts that the stuff in the manifold is related to your issue.

When was the fuel filter last changed?

Jack

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Paul
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Re: Truck won't rev

Postby Paul » Thu Aug 23, 2018 11:25 pm

Skropeling wrote:I have this strange issue happening right now. When I give my Pup more throttle, it just shoots out black smoke rather than increasing the RPMs. My mechanic says that the injector pump went out, and that the engines in those trucks die pretty quickly anyways, so he just suggests scrapping the truck for 100 bucks.


I can't agree with your mechanic. These engines and injection pumps are known to last. Don't give up on it.

Question. Does the engine idle normally; ie, without black smoke?

I pretty much agree with Jack that the accumulation in your manifolds and head are probably not the problem.

Lots of black smoke without accelerating suggests that the engine is starved for air. This can happen if any part of the intake is plugged up or if the exhaust is plugged up.

You can try removing the air filter (be careful as things can get sucked into the intake). And, you can try to remove the down pipe from the exhaust manifold.

More info would help.

Paul
'84 P'UP 2 wd diesel, 5 spd with 0.78 fifth gear and differential back to 3.73.

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Re: Truck won't rev

Postby FiatSpider2 » Fri Aug 24, 2018 7:27 am

Surprised you didn't have a run-on with all that oil in the intake.

Before you go too crazy you may want to disconnect the muffler in case its gotten restricted and if that resolves it then you'll need a new muffler and possible a smoke valve adjustment. You probably do not want to force anything through the cylinders by towing the truck to get it to high rpm as you will chance scoring the cylinders and further plugging up the exhaust.

Too many take these 1/2 million mile engines apart looking for something major before ruling out the simple things.

When the compression test was done after replacing the head gasket what did the numbers indicate?

Putting straight Dexron I or II ATF through the injector pump to clean and lubricate it probably wouldn't hurt either.
FiatSpider2 (4FB1 Isuzu Diesel powered 1978 Fiat Spider)

dorf
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Re: Truck won't rev

Postby dorf » Fri Aug 24, 2018 9:08 am

Will your fuel filter/water separator pump up and hold prime

If not.....there is a air leak. In the suction side of the fuel system

Just my 2 cents

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Re: Truck won't rev

Postby 2sk8 » Fri Aug 24, 2018 1:46 pm

Wow, that mechanic told you to scrap the truck for $100, what a moron, seriously.

Don't listen to the fast talking swindlers.

Anyway I'm thinking you have a clogged fuel filter. Sounds like you injection pump is not getting enough fuel somehow.

When did you change the fuel filter last time?

I will check the fuel filter first and then move on checking the inlet and outlet fittings in the pump itself.

They may be clogged.

Also check that the return fuel line is also free flowing, blow compress air thru it.

I think you have a fuel restriction some where.

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JoeIsuzu
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Re: Truck won't rev

Postby JoeIsuzu » Fri Aug 24, 2018 4:43 pm

Skropeling wrote:...it just shoots out black smoke rather than increasing the RPMs...

Paul paid more attention to this than I did, the first time I read through it. I think this tends to suggest something besides fuel starvation--unless a restricted fuel filter can affect timing advance, etc.

Jack

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Paul
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Re: Truck won't rev

Postby Paul » Fri Aug 24, 2018 6:28 pm

JoeIsuzu wrote:
Skropeling wrote:...it just shoots out black smoke rather than increasing the RPMs...

I think this tends to suggest something besides fuel starvation--unless a restricted fuel filter can affect timing advance, etc.

Jack


Fuel starvation will prevent the timing from advancing and this will lead to smoke. But, his truck will not rev beyond idle with no load and still smokes. I am pretty sure that failure to advance (alone) will not cause this. And, if the available fuel is only sufficient to idle I don't think it could smoke heavily when the throttle is advanced.

Another thought.

"When I was changing my head gasket (which is what somehow triggered this issue)"

Is there any chance that you left a rag in the intake manifold when working on the head?

Paul
'84 P'UP 2 wd diesel, 5 spd with 0.78 fifth gear and differential back to 3.73.

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Skropeling
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Re: Truck won't rev

Postby Skropeling » Sat Aug 25, 2018 3:30 pm

Thanks for the help, sorry I couldn't get back to you sooner. I've already replaced my fuel filter, so I think we can narrow it down to the intake / exhaust (I've already ran transmission fluid through the fuel system too so the lines should be good). I'm going to give my mechanic a call, I'll have him put my truck back together and I'll tow it home. Once it's home, I'll try taking off the exhaust and maybe the intake manifold. I could also take a video of the engine attempting to run and post it on youtube, maybe seeing the issue will help solve this issue.

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Skropeling
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Re: Truck won't rev

Postby Skropeling » Sat Aug 25, 2018 4:22 pm

Oh sorry, I didn't answer a few questions.
Paul - No, it does not idle normally. I don't have a tachometer, but I would guess that it idles below 300-400 RPM. You can pretty much count the revs, that's how slow it idles.If it helps, the truck ran pretty good before all this started. It was getting slower and putting out some smoke, which is why I tried the head gasket change. Turns out I had a bent push rod, so that's most likely what was causing the lower speed / smoke.

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puttputtinpup
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Re: Truck won't rev

Postby puttputtinpup » Sat Aug 25, 2018 7:08 pm

Jumped time causing the bent pushrod?

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Re: Truck won't rev

Postby 2sk8 » Sun Aug 26, 2018 11:46 am

Who knew, a bent push rod...

Thanks for sharing. Now We know what else to inspect for when the engine is acting strange like yours was doing.

I think you should check the timing marks and timing belt and why you ended with a bent push rod.

Please share what else you find.

Glad you found your problem.

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Skropeling
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Re: Truck won't rev

Postby Skropeling » Mon Aug 27, 2018 6:33 pm

I got my truck back from the mechanic today and started it up. same issues as before. I got a video of it, maybe it will help.

https://www.youtube.com/watch?v=rk0D1MzEHQw

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Skropeling
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Re: Truck won't rev

Postby Skropeling » Mon Aug 27, 2018 6:49 pm

Ok, I inspected the liquid coming out of the pipe and it is oil. This has to mean I did the head gasket replacement wrong right? I can't imagine what else it would be. I don't see how I could get it wrong though, but I guess I could've.

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JoeIsuzu
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Re: Truck won't rev

Postby JoeIsuzu » Mon Aug 27, 2018 8:12 pm

Sorry, I'm having trouble following all this. I got the impression that the bent pushrod was the problem. That's what I thought "Turns out" meant. Looks like others thought the same.
Skropeling wrote:Oh sorry, I didn't answer a few questions.
Paul - No, it does not idle normally. I don't have a tachometer, but I would guess that it idles below 300-400 RPM. You can pretty much count the revs, that's how slow it idles.If it helps, the truck ran pretty good before all this started. It was getting slower and putting out some smoke, which is why I tried the head gasket change. Turns out I had a bent push rod, so that's most likely what was causing the lower speed / smoke.

So you replaced the head gasket, and then you found a bent push rod? That was replaced, right?

Can you try to break this down for us, play by play?
Each step you took, and the result. In order.
A little more detail than "head gasket change", too. Was the head milled or checked?

Jack