6.5 SHUTS OFF IN FIRST 20 MINS.

[Scooby]

I just bought a beautiful 1996 1500 with the 6.5 TD. When I went to the lot to test drive it, it cut off when the salesman parked it to go inside & get a plate for it. Long story short- truck was spotless, and had just under 100k. I bought it, and have been frustrated since. It shuts off at idle, or at highway speeds, but only within about the first 20 minutes (15 miles) of driving, after it has sat for several hours, or overnight. If I put it in neutral, turn the key off, then restart it, it usually runs ok. Sometimes it is hard to restart. I have changed fuel and air filters, checked fuel for water, and looked over the electrical connectors behind the fuel filter. I also changed the fuel lift pump just in case. Still have problem. After 15- 20 mins driving, it runs fine. Vacuum pump is pulling 24" .I did notice someone has opened up the wire harness behind the fuel filter, and hooked two black wires to ground on one of the intake studs at the fuel filter. Also, I am getting only about 17 mpg on the highway in FLorida (no hills!!) with no topper or trailer, driving about 70 mph. I think it should do better.

Any ideas ?? I called the service manager at the local CHevy dealer-- he said it sounds like injection pump- which would be under warranty from what I can tell.

Rick

[charliepeterson]

Yes you are covered for 20,000 more miles on the Injection Pump and PMD (electronic pump driver). You still have untill 2007 on time (11 years/120,000 miles).

No deductable!!

Special Policy #00064D

[Turbine Doc]

Hey Scooby, welcome to the site, if the dealer swaps out the pump under warranty, see if you can get him to give you the PMD/FSD off of it, couple of us here are trying to do some data collecting on PMD fails, if he won't let you have it, check and see if he will let you take the PMD off.

Under the plastic transistor covers are 2 nut's/studs theory is that they loosen after a while, it would be good to know if those are still tight or have backed off as some have found

[Scooby]

Thanks for the replies so far. I am going to take it to the dealer when I can get home in time so I can talk to the service manager. What about fuel mileage?? I drive a lot of miles, empty, no hills in central Florida. 17 MPG. What do you guys get???

[cubby]

Sounds like you have a fuel leak,and your sucking air to the line. I don't know what kind of a manifold you have on your filter, but that is where I used to have problems with leaks.
I've switched all of my trucks to a screw on fuel filter and have never had a problem since.

[richard7]

What is your rear end ratio? Tire size?
Typical 3.42, 245/75/16 = 20 MPG
3.73, 245/75/16 = 17 MPG
4.10, 245/75/16 = 15 MPG

[turbovair]

Im getting 16-17 MPG highway. Take a look @ my profile.I think your mileage is right on par(if you have 4.10 gears)

[G B Sisson]

How do I find my axle ratio? There's a sticker on inside of drivers door but all info is rubbed off... 94 2500 4x4 Sub. Thanks , Gary

[Scooby]

Thanks again for the replys so far. I have an Amsoil/Dahl water separator/ 2 micron filter I intend to install soon. I am taking it to the dealer tonight to see what they find. I am going to check axle ratio too. Tires are 30 x 9.50 x 15 . Is the fuel inlet line to the pump 3/8" ?? THats what it looks like. I havent had much time to mess with the truck- got to work too !!!

[Turbine Doc]

GB look in your glove box RPO codes alpha numeric code GT4=3.73 GT5=4.10, GU4=3.08, GU5=3.23, GU6= 3.42 HC4=4.56, G80= limited slip

[Scooby]

I did the old mark and spin- I have 3.42 gears. The tires are 30 x 9.50 x 15. I should be getting better than 17mpg empty !!

RIch

[G B Sisson]

Thanks tbogemirep, I have 3.73 gears. Here is a formula I have used for years and will determine engine RPM @ 60 mph.Now that I think about it it will not be accurate for overdrive,and not sure about automatics...but it's good for comparison. It assumes a 1/1 final transmission gearing......Tire Dia times 3.14 divided by 12,then divide into 5280 then multiply by your axle ratio equals RPM @ 60 mph.....With this you can see what kind of difference a change in tire dia will make. I'm sure someone on the Page can ammend this to work on our current transmissions.( My notes show that back in the 70's I dropped almost 300 rpms on my landcruiser pickup by going from a 700/15 to a 750/16 tire) looked cooler too Gary

[Gapper_ca]

have a 96 as well.
not sure on your tire size but i run 245/r70 16's

at 60 i get around 22 -24 at 70 tho i get about 18-19

if yuo want better milage have to slow down some and have tire pressure up.
also if a/c is running will drop a alittle.

[Scooby]

The 30's on my truck call for 50 psi, and thats what I have in them. I usually drive about 70 mph. With 3.42 gears I think thats 2100 rpm.
GOOD NEWS FROM DEALER-- There were 3 codes indicating IP failure. New pump will be in tomorrow. The screws on the FSD were all tight according to the service manager.

[chickenhunterbob]

My truck is a little older, 1994 Silverado 1500 6.5TD 4WD with 3:73 gears, 265 75 R16 tires and no mods, and at 62 MPH (100 KM) highway miles with very light load (two dogs in a box) I consistently record 23 - 25 MPG per tank, with occasional wind aided highs of 26 - 27, but those are rare.

This is calculated in imperial gallons which are slightly larger than US gallons, so a quick convert would be 24 MPG (imperial gals) would equal 20 MPG (us gals).

At 62 MPH the tach is about 1900, which according to the diesel primer is slightly above the 1800 recommended for best fuel mileage.

I wish I had 3:42 gears, I maybe could drive 70 MPH then too, but obtaining best fuel mileage is sort of a consuming hobby of mine, and keeping the tach under 2000 seems one of the most effective and cheaper alternatives.

regards

[G B Sisson]

I have 255 85 / 16s on one of my other trucks. They are 33" without being overly wideand fit stock rims easily.This is about1 1/2 " taller than what you are running and without doing the math, should drop about 150 rpms off the tach at the same speed......but will they clear?