93 6.5L TD - No warm start

[MMayhem]

Hi,
1993 Chevy 6.5L TD - 160,000 miles
Truck will not start if engine is warm.
Looking for any additional advice before I try fixing this problem.
Starts great cold and runs mighty fine.

Workaround: cool water poured on the Injector Pump, wait 30 sec, truck will start.

I think the Lift Pump is not working.

Plan to replace fuel filter and OPS first ... and then bleed lines. Do I only bleed from the fuel filter cap and the front bleed valve for removing water?

Then, if not successful, will replace the lift pump. Is there also a relay that operates the lift pump? Where is it?

Then, if not successful . . . I will take it to a mechanic to replace the IP ($80/hour) :(

If IP needs to be replaced, should I order a rebuild IP from realdiesel.com for $450? Are they reputable? Anyone have experience with them?

Thanks much for any responses . . .

-Mark

[More Power]

The air bleed on top of the filter is used to bleed any air from the filter after replacement.

The lift pump relay is only energized while cranking the engine.

Have a look at the Troubleshooting Guide for more info on hot start problems.

http://www.thedieselpage.com/members/guide.htm

MP

[MMayhem]

Thanks for the reply!
Well, I have read about every post on this site . . and the Troubleshooting Guide.
Terrific amount of information!

This is what I get from it regarding my warm start problem:

1. Replace Fuel Cap (or release vacuum on every shut-down). Vacuum in tank may be drawing fuel out of the lines.
2. Replace OPS. Then I will again hear that familiar "purr" of the lift pump for 2-3 seconds after shut-off.
3. Replace Fuel Filter . . well this is the FIRST thing.
4. Replace Fuel Pump Relay. Fuel Pump Relay should be found by Glow Plug Controller and well marked/identified.
5. Consider bypassing the Glow Plug Inhibit Switch that prevents Glow Plug operation when Engine is warm. Cheaper than replacing the controller.
6. Then maybe replace the Fuel Lift Pump . . . might be getting weak or letting fuel drain back out of system.
7. I should be able to get 250,000 on IP and Injectors, so this is definitely the LAST RESORT smile.gif

A very "amatuer" mechanic, such as me, should have no problem with all but Item #7

Any additional advice is certainly welcome

Thanks,
-Mark

[CoachWagner]

I had the same stalling problems and did the cool water thing for a few months but eventually I had to change the FSD. That did the trick. 4 months and no problems with warm starts anymore. I did it with the help of a mechanic friend but it really was not as hard as I though it would be. Didn't see that in your list but it solved my problem. :D

[Polar Diesel]

Sounds like you've got a wore out pump. It just can't pump that thin hot fuel like it used to. I presume it's a 4911 pump if it's a 93. 250,000 is stretching it for pumps like these.

[bobt]

Hi. I also had a hard warm starting problem with my '93; however, I only had about 65,000 miles on mine. Problem was a bad glow plug controller. Your problem may be the IP with your miles, but if you replace the IP and still have the problem, I'd bet then it's the glow plug controller. Good luck in your search for the cure.
Bob

[cruzer]

MMayhiem, sounds like your on the right track.
Disregard the comment on the FSD. You don't have 1. Also you probably don't have a glow plug inhibit switch. If you look in the trouble shooting guide under Glow plugs or cold start for your yr and earlier it will go into detail on when it was dicontinued. That operation was taken over by the glow plug controller.I don't recall fuel pump relay too. I think the OPS takes its place and operates the lift pump.

[MMayhem]

Thanks much for the replies!

Polar Diesel: yes, it is a 4911, but truck runs great . . no misses and good power. I agree the pump is probably weak because cool water on it will allow the truck to start. But, I am trying to follow the advice of all alternatives prior to replacing pump. . . and hope'ing

cruzer: thanks . yea 93 doesn't have a FSD and I cannot find a fuel pump relay anywhere, though the parts store had one to sell me. First thing I will replace is the OPS. I do not hear the lift pump operating like it used to when shutting down the truck . . so I think that will help.

Bob T: yupp! . . I think once I get the lift pump working with new OPS. . . the second priority will be the Glow Plug Controller. After the truck sits for 2 hours, the glow plugs operate and the truck starts fine. I do not think I am getting the glow plug operation that I need when the truck is warm. I just thought ovverriding the inhibit switch (if there is one) would be cheaper and a more "sure" fix.

CoachWagner: Thanks, but no FSD on this machine. Fortunately there was a problem with FSD's on later years because that vast internet info (mostly sales) on it caused me to search further into the vast internet resources available for troubleshooting 6.5L turbo diesels! . . and eventually this terrific site!

Thanks again . . it is my next weekend project, so any more advice is certainly welcome.

[Polar Diesel]

The reason i go for the pump is when you cool it down it works fine. I have a tractor that does the same thing, brand new engine, old pump, starts great cold, but work it for an hour and your lucky to get it started for an hour. Wore out hydraulic head.

[bobt]

MMayhem, for your comparison, my warm start problem symptons were that between 45 minutes and about hour and 15 minutes, it wouldn't start when warm. Any sooner or any later and it would. It acted like the engine was not hot enough to start without the glow plugs, but was too warm to initiate the controller to light the glow plugs. All I had to do was wait until it cooled off more (at times very inconvenient), get just the slightest hit of glow from the plugs and it would immediately start. Replaced the controller and problem vanished. If your symptoms are similar, this might fix the problem. I had my engine very hot several times prior to this problem occurring and the problem got worse as time went on. I think the excessive heat may have damaged the controller.
Bob

[MMayhem]

Thanks Bob . . . that is exactly the condition I am seeing. . . except about 1/2 hour to 2 hours is my window of no warm start
I appreciate the advice!

[Polar Diesel]

but what does the glow controller have to do with cooling th epump off with water??

[bobt]

Polar diesel. As far as I know, there is no relation between the two. If the pump is worn, heat expands the clearances and the water cools and shrinks those clearances. In my case, the problem was not the pump, it was a faulty controller.
Bob

[Bobbie Martin]

Check with a Stanadyne dealer. There are known hot start problems with the early 6.5 head and rotors on the DB2s. Sounds like rebuild time.

[MMayhem]

I agree it will probably lead to a re-build eventually, However:

-All articles on this site stress to eliminate all other possible problems before rebuilding IP
-Article here states that 50% of IP rebuilds were NOT required as tested by GM Warranty service.
-My lift pump is definitely not working (may be OPS or bad lift pump)
-The truck will start if there is Glow Plug (engine is also cooler of course)
-Based on all this, I am assuming the a STRONG IP can overcome this other failures and still start, but if I fix these other failures first . . the weak IP may be adequate.

IP repair: $1200-$1500 :(
All other stuff to try: <$300 smile.gif

I have got to try everything else before rebuilding IP

Thanks again for all the advice

[MMayhem]

IT'S FIXED!!! smile.gif

This forum saved me a fortune!!! Thanks all!!

Replaced the OPS ($10 for a OPS socket for my rachet wrench)

Replaced the Elec Lift Fuel Pump (I'm gonna smell like diesel fuel for a week! Is there a fuel tank shut off I could have found?)

And . . replaced the fuel filter

Bled the lines . . not NEAR as hard as the mechanic said it would be.

Tried a number of warm starts this afternoon at different wait intervals

Starts up every time! . . . . so IP may be weak, but the good OPS and strong new lift pump solved the problem!

[CareyWeber]

Originally posted by MMayhem:
IT'S FIXED!!! smile.gif
Replaced the Elec Lift Fuel Pump (I'm gonna smell like diesel fuel for a week! Is there a fuel tank shut off I could have found?)
Starts up every time! . . . . so IP may be weak, but the good OPS and strong new lift pump solved the problem! I have short pieces of rubber fuel line going to and from the filter before my lift pump and a pair of vicegrips makes a perfect shuyoff.

Great news that you got it going!!!

Carey

[MMayhem]

thanks for the tip on shutoff! . . next time for sure!
Then, maybe wifey won't make me sleep on the couch!