oakme2

I have a high mileage 657K 90 model with the VE pump. I got it when it had 234K on it and am not sure about its history. It did overheat and blow a head gasket at about 575K miles, you could still see hone marks in the cyls, which I couldn't hardly believe. That was about two years ago. In the past 6 months it has started loosing power. It has gotten so bad that takes me about a half mile to hit 65, that is unloaded. Once I get up to speed it seems to do better but still weak. It did run 82 mph now it tops at 70 on a long long straight unloaded. It starts super quick, any time hot or cold, and doesn't smoke noticeably. The engine has no noticeable blowby. The lift pump is working great, so I guess the old VE has worn out. It runs like it did when the small tube broke that goes from the intake to the top of the inj pump where the diaphragm is. I have the diaphragm turned for max fuel, I did this when it started loosing power. I was wondering if these VE's normally drift out of time because of wear. I know that is a long shot. I was planing to rebuild the old motor and pump mid summer, and I don't think it is going to make it, and I need another 3 or 4 thousand miles out of her. Any Ideas?

Tobin

I would have the pump and injectors tested. I would also check the turbo and make sure you don't have a boost leak.

Tobin

wannadiesel

Check to be sure the throttle lever hits the high speed stop when the accelerator is floored. This causes most "low power" 1st gen trouble.

How long has it been since you changed the fuel filter?

It does not sound like an internal engine, pump, or injector problem to me. Tired VE pumps idle slow and die when hot and don't want to restart. If the engine was tired it would be hard to start and have lots of blowby. What you have is a minor external issue that will be easily fixed once you find it.

RollinCoalSmoke

I agree with wannadiesel. Check your turbo & hump hoses first. I'm leaning towards turbo though. Does it smoke? Can you hear your turbo at all? If it's your hump hoses you should be able to tell quickly because it will probably be a big leak. My buddies truck blew a hump hose and still had some power but smoked. Pull your intake hose off and take a look at the turbo to see if it's turning or has any fin damage. Buy a cheap set of guages to monitor with and it can save alot of headaches. oakme2 I hope I get that many miles on mine. Good luck.

Jim Lane

What kind of transmission do you have? If it is an automatic you could have a locked up torque converter not allowing to multiply but to drive directly coupled.

Fuel pump sucking air?

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Jim

oakme2

It is a 3 speed auto, the converter feels fine. It's quiet, stalls well and doesn't give me any signs that it has trouble. I can't find a pressure leak in the pressurized side of the turbo. If you punch it a few seconds and let off the turbo has always whined just a little like a siren, it still does this so I know it is spooling up. The impeller shaft doesn't have excessive slack. The miles this engine has lasted have amazed me, it has been worked hard but well cared for.

The fuel filter has about 5K miles on it. I stopped up a filter crossing the Mojavie desert in the summer when I got some bad gas, so I know what that feels like, or at least that time. It feels like the engine would hit a wall, and if you tried to throttle it past the wall it would just fall flat out. As soon as you let off it would run fine and idle. That is until you throttled up again past a certain point. Is that what a stopped filter usually does on one of these 90 models, or can it just maybe rob power?

Sucking air, that could be it. I was also thinking that the diaphragm in the top of the VE might have bailed.

What about the timing, with all the miles I have on her. Does the timing ever drift out of spec and cause these problems. I have a spare engine with 99K miles and a spun #6 rod bearing I bought for parts. I was about to pull the VE off of it and try it.

schamran

Not to insult your intelligence, but did you try replacing the fuel filter? Mine lost power b/c of a dirty filter.

oakme2

No insult, good point. No is the answer because it doesn't feel like the way this truck has acted in the past when there was a stopped up filter. Now that might not mean a lot. When the filter stopped up before it felt like the engine was hitting a Governor with full power all the way up to the point where it completely dropped off.. Has any one had a stopped up filter on one of these where it made it weak, and it would rev ok.

schamran

Yup. Everything seemed fine until you hit a hill. There was still some smoke, but not like normal. That is a good indicator by the way, if your pump is turned up. Smoke = fuel.

Jim Lane

Is there any chance that you might have a restricted exhaust?

You might want to pull the AFC diaphragm and look down the bore and watch the small pin from the left side, see if it moves freely to ride up and down the taper on the fuel pin, it might be sticking.

You haven’t run any Biodiesel recently have you?

Does it do the same with different levels of fuel in your tank to rule out a cracked pickup?

oakme2

Ill try the filter first. If that doesn't do it I will check the AFC diaphragm, and the pin. No biodiesel, and the exhaust is straight 3 inch with no muffler out the back. I have seen double wall exhaust pipe with the inner wall collapse and restrict, I will have to keep that in mind. It acts the same with all levels of fuel in the tank.

RollinCoalSmoke

oakme2 does it smoke anymore/less than before? If so has the smoke gone from grey/black to a white haze? Might be a chance of it sucking air pre lift pump. Does the injection pump have any leaks?

oakme2

The smoke is about like it was. It is black It is so close to stock so, it doesn't hardly smoke. Because of that I haven't hardly paid much attention to the smoke. I looked at it real good externally without taking ant thing apart. It looks like there is some very minor leakage around where the fuel filter mounts. That area should be under pressure where it cant suck air. I am going to take the suction hose off of the lift pump and put it in a 1 gallon can of diesel and drive it to see id the fuel system is sucking air between the lift pump and the tank.

wannadiesel

No, the VE pumps have the timing gear keyed to the shaft. They don't slip like the P-pumps.

RollinCoalSmoke

oakme2 any place fuel can get out air can get in. Sounds crazy but it can. Check your fuel system real close, suction tube to the injection pump. I would have bet it was a hump hose or turbo going down. But now it becomes a real find the pin in the haystack thing. Let us know what you find or don't find. Good luck.