# 94 6.5 turbo diesel hard start



## Jim Gaudioso (Jan 8, 2001)

I have a 94 turbo diesel w/ 50k. After driving other diesels seems like this thing takes forever to start. I check all the basics glow plugs, glow plug relay, air and feul filter. Truck has 2 new high amp batteries. Once running engine runs strong. Hooked up my scanner no codes.
checked the running stream and the only thing I found out of range was the engine temp. I went ahead changed sensor.
checked all the wiring etc. to the manual specs. still reads out of specs. 1)How many seconds after glow plugs are ready should this truck take to fire. 2)Could I have a bad computer that may be throwing off the fuel and air delivery at starting? any suggestions please advise.


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## plowking35 (Dec 21, 1999)

Mine takes about 3-5 seconds of cranking after glow plugs go out, on the coldest mornings. Once warm, 2-3 secs at most.
Check the lift pump, along the frame rail, to make sure its working. If its not, the pump will be starving for fuel.
Dino


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## TLS (Jan 31, 2000)

Jim,

Can't really help you on this one, however, I know what will! Go to http://www.thedieselpage.com If you own and enjoy GM diesels, membership here is a must. Its only $15.95 per year. There is a forum on there that has a lot of categories. Your problem surely has been shared by many people there and they will steer you in the right direction quickly. Well worth a look.

You said you checked your glow plugs? How? They have had many changes in glowplug types over the years. The newest are bulletproof. You may have 1 or 2 not working. As cold as its been in the NE, plugging in is important unless its in a warm garage.


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## steveair (Feb 24, 2000)

Hello,

Not sure, but I would sbegin with cold temps and the need to have the truck plugged in overnight. 

If you did this, I would then maybe check your fuel. Though it should be, sometimes you get a tank of diesel that doesn't have the proper additives, and may be getting some gelling to occur in the fuel. Maybe try a diesel conditioner, as we had this problem at work just the other week. We have a 98 6.5, and it wouldn't start for over a minute of cranking. Finally discovered the fuel problem in our big tank when we filled up another truck.

If not one of these simple things, then things are probably a little more complicated and I'll others take it from here.

steveair


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## John DiMartino (Jan 22, 2000)

It sounds like yor lift pump is going bad,to check it,when you pull the fuel filter,have a friend put the truck in neatral and and turn the key to crank while you are looking inside the fuel filter housing.When he turns the key to crank,this energizes the lift pump,since the truck is in N it wont crank though,the fuel filter housing should fill up in about 5 seconds at the most,if it doesnt fill or takes a long time,the lift pump is bad.If it needs one,dont put it off,this stresses the main pump more,causing early failure.My Dad's 94 always started hard,when we were changing the filter for the first time,it wouldnt fill when we jumped the pump,thats how we figured out it was bad.The pump is easy to change its on the frame under the drivers door,and looks like a fuel filter with wires going to it. Good luck.


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## John DiMartino (Jan 22, 2000)

Forgot one thing-GM sent my dad a letter right brfore he traded his in,it said they were extending the warranty on the fuel system to 11 yrs or 120K.If your under 120K,maybe you should jus take it to a GM dealer if you think its the lift pump,I think they are arouind 225 bucks,and deductable is only 100,,trhen they'll get all stinky doing it too,not you.My uncles 96 6.5 has never given him trouble since it was new(exept starter motor,when it was 3 months old),in the last 2 months,the lift pump went,then last week it was towed in,fuel pump went,it has 90K on it.


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## plowking35 (Dec 21, 1999)

John any fuel system related repairs are not subject to the 100.00 deductable.
Quote from my letter"
"If this occurs with in 11 years of the date your vehicle was originally placed into service or 120,000 miles(193,00 km)whichever occurs first, the condition will be repaired for you at no charge."
Dino


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## Jim Gaudioso (Jan 8, 2001)

*94 TURBO DIESEL*

GUYS, THANKS FOR THAT INFO
TWO OTHER QUESTIONS,DOES THE WARRANTY COVER YOU IF YOU PURCHASED THE TRUCK USED? SECONDLY IS THERE A WAY TO CHECK THE LIFT PUMP WITHOUT TAKING OUT THE FUEL FILTER. IS THERE A PORT WHERE I CAN TEST THE FUEL PRESSURE WITH A GAUGE?


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## plowking35 (Dec 21, 1999)

As long as truck is with in warranty guidlines, what owner you are doesnt matter. Pulling the fuel filter is an easy process, it is located under the pump cover in the center of rear of "intake".
At normal cranking speed,the minimum allowable pressure measuered at the outlet side of lift pump is 2 psi, and the flow should be at least1/2 pint in 15 seconds. Typical electric lift pumps will deliver 4-6 psi and at least 1 pint in 15 seconds. Having both proper fuel pressure and volume are equally important for ease of starting.
Taken from the 6.2-6.5 diesel trouble shooting guide.
Other possible causes of hard starting.
1- Fuel Filters
2- Battery voltage
3- Glow plugs and controller
4-Fuel line air leak
5-Cold advance and fast idle functions
6-Injection pumps and injectors
7-Elevation
8- Fuel Quality
9- Engine Decrompression
Dino


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