I have a 99 F250 7.3 diesel and when the truck is under light load (ie. driving 80km/h criusing when I start up a hill and need that extra bit of power the truck shakes like crazy unless I floor it). Does anyone have any suggestions?

Thanks Mike

 

Would suggest you have your fault codes read.. might give you a clue on whats going on..

 

I have had it checked and nothing that would cause that came up all their was, was air intake heater, air bag, something to do with the radio and glow plugs. It has me stumped and I refuse to pay 100 bucks per hour shop rate to get it looked at as I can't afford that lol.

 

Does it always vibrate or shake when you are moving os just when you give it some gas?

 

I had the same symptoms with one bad injector. No SES light, idled fine but would vibrate when trying to accelerate from 45-60 mph in top gear.

How many miles do you have on your engine? Stock injectors?

 

196,000 and as far as I know yes

 

Is their any way to diagnos this issue or just buying them and replacing them?

 

^KUPAA^
It is only shaking when on the gas if I just coast that that speed it is fine

 

Yes. If you have access to a scan tool such as Auto Enginuity, you can run some injector tests and also rule out some stuff. Everybody with a high mileage PSD should get this software because it pays for itself pretty quickly.
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Short of that, you can try a few other things. First of all, confirm your oil level is correct. Low oil can cause all kinds of weird symptoms. I then recommend you check your wiring harness. The main IDM connector has some dielectric grease from the factory and after 10 years it dries out and becomes flaky. Clean it with some electronics parts cleaner and apply new dielectric grease and do the same with the body to engine harness connector (Driver's side, below your IC and intake tubes). Also make sure your connectors at the valve cover harnesses are clean as well.

If that doesn't help anything, then your next step might be to look under the valve covers themselves. The under cover harnesses come loose all the time so you want to look at that first. Should be a nice tight fit. If you haven't done so already, install the Ford plastic clips to keep the harness from coming loose or perform the 50 cent mod. Do a search and you will find more info.

Then, while you have the valve covers off, start the engine and look at the oil discharge for each injector. You may find one or more injectors with abnormal discharge (too little or too constant). Both are bad.

You might also have a bad solenoid but that usually throws an SES light on your dash.

Good luck!

 

Ok thats awesome thanks Ill start looking at stuff this weekend when I get some time to do so. Your information is very helpful and appreciated

 

So I finally had the time to pull my truck apart and the 50 cent fix worked awesome. Thanks to everyone who gave me the advise. It was the best 50 cents that I spent (as well as the 170.00 for glow plugs lol) A big thanks to everyone who helped.

 

Great news.. !! Mine came apart at 70K.. and did the 50 cent fix.. been good ever since..Thx for reporting back ..