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Hello, I have used this forum lots, but am a new member. I have done a fair bit of research on the question I am going to ask, and I have learned allot! However I cannot find an answer to, what i think, is a fairly simple question (hopefully).

I have a 1993 6.5, it does not have a PMD. I am going to replace the Lift Pump and OPS tomorrow hopefully as I am sure the need to be replaced.

The Truck does have a bit of a tough time starting. I usually have to run the glow plugs once. Turn it over 1-2 times. Then repeat. After the glow plugs run the 2nd time and I turn it over, it usually starts up in a couple turns with no issues.

If I have been driving the truck lots, and it gets hot or fairly warm, and I shut it off it will be VERY hard to start. Sometimes it will not start at all. So, I take some water and pour it on the engine. After a minute or so, if i try to start the truck it will fire right up. I am assuming this is because my injection pump is failing? probably because my lift pump/ops are not working properly (due to the harder starts?)

I am also noticing power surges when I accelerate. It can feel like its bogged down or lacking power, then all of a sudden it will have a surge of power, then return to that bogged down feeling again. Generally just cruising down the road the truck runs great but does feel like its lacking a fair bit of power. ( i intend to do a optical bump once this issues is fixed).

Now the question. If this IS my injection pump, will just buying a rebuild kit fix this issue, or do i need to get a new injection pump all together? I dont see any fuel leaks etc around the injection pump as it is.
 

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Welcome to DieselPlace

If you experience some hard starting while the engine is warm and then pour some water on the IP and it starts, that is a sign of a worn-out Injection pump.
Lacking power or surging can be air in fuel, Lift pump/OPS issue or worn Injection pump.
The Optical bump you mentioned is for the DS4, electronic IP with the PMD.
Your IP should be a DB2 mechanical

If you rebuild your IP you would need some specialized tools for the internals.
 
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Welcome to DieselPlace

If you experience some hard starting while the engine is warm and then pour some water on the IP and it starts, that is a sign of a worn-out Injection pump.
Lacking power or surging can be air in fuel, Lift pump/OPS issue or worn Injection pump.
The Optical bump you mentioned is for the DS4, electronic IP with the PMD.
Your IP should be a DB2 mechanical

If you rebuild your IP you would need some specialized tools for the internals.
thank you for the reply. riiiiight, i should of known i cant do the optical bump on mine. I dont think i would rebuild it myself. Will rebuilding the Injection pump fix the starting issue when it is hot however?
 

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thank you for the reply. riiiiight, i should of known i cant do the optical bump on mine. I dont think i would rebuild it myself. Will rebuilding the Injection pump fix the starting issue when it is hot however?
A rebuilt or new IP can solve the hot start issue.
What is happening is that the seals inside of the Injection pump go out of spec due to the heat and the cool water brings the seals back into spec and your IP works as normal.

First, go through and check your entire fuel system from tank sock to IP and fix any fuel system issues ( leaks, dry rotted lines, corroded line, blockages etc. )
Check your fuel cap. Open your cap and if you hear a large "Whoosh" sound then you have a restriction and need to modify your cap for better venting.
Install a piece of clear fuel line on the return side of the IP ( as shown in the link) to help locate any air in fuel gremlins.
If you notice any air bubbles within the line then you need to hunt the source of the air intrusion.
Go through all of your ground wires: Grounds-Grounds-Grounds The importance of good grounds.....

Also, since you live in a colder climate I would install fresh glow plugs, go through all of your glow plug wiring and install the Glow plug override to help give you more glow time manually for easier starts:

Once you have gone through these steps and still have issues then you can start to lean towards the IP being the issue
 

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Discussion Starter #5
A rebuilt or new IP can solve the hot start issue.
What is happening is that the seals inside of the Injection pump go out of spec due to the heat and the cool water brings the seals back into spec and your IP works as normal.

First, go through and check your entire fuel system from tank sock to IP and fix any fuel system issues ( leaks, dry rotted lines, corroded line, blockages etc. )
Check your fuel cap. Open your cap and if you hear a large "Whoosh" sound then you have a restriction and need to modify your cap for better venting.
Install a piece of clear fuel line on the return side of the IP ( as shown in the link) to help locate any air in fuel gremlins.
If you notice any air bubbles within the line then you need to hunt the source of the air intrusion.
Go through all of your ground wires: Grounds-Grounds-Grounds The importance of good grounds.....

Also, since you live in a colder climate I would install fresh glow plugs, go through all of your glow plug wiring and install the Glow plug override to help give you more glow time manually for easier starts:

Once you have gone through these steps and still have issues then you can start to lean towards the IP being the issue
That is super awesome. I’ll start doing all that. I appreciated your reply, it was extremely helpful.

I put a glow plug override switch in this last winter haha

ty again
 

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Head and rotor is bad. Major rebuild required. Gasket kit will not fix it.
i had a feeling this might get said. is doing a "major" rebuild worth it? how much cheaper would that be than getting a new one. and would it still be very reliable? im assuming getting a major rebuild done should be fine but i better ask just in case!
 

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All the 93's and some 92's had a manufacturing defect...Some worse than others. Hard start when hot/ Or heat soak problem. The H&R would not pump fuel after a few minutes of heat soak. One way to tell was to pour water over the IP and let it sit a minute or two and try to start. If it started the H&R was bad. A new H&R is expensive and most shops replace the H&R with a rebuilt unit which is still expensive. GM even had an extended warranty on those trucksi to help wash their hands of the problem back in the day. In any case when replacing one of those pumps with a reman ask if the H&R was changed out. The choice is yours.
 

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Discussion Starter #9
All the 93's and some 92's had a manufacturing defect...Some worse than others. Hard start when hot/ Or heat soak problem. The H&R would not pump fuel after a few minutes of heat soak. One way to tell was to pour water over the IP and let it sit a minute or two and try to start. If it started the H&R was bad. A new H&R is expensive and most shops replace the H&R with a rebuilt unit which is still expensive. GM even had an extended warranty on those trucksi to help wash their hands of the problem back in the day. In any case when replacing one of those pumps with a reman ask if the H&R was changed out. The choice is yours.
ok so the H&R is the head and rotar im assuming? From what i have researched since reading your comment is there is now new H&R units available to fix this hot start problem?
 

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As soon as Stanadyne realized their mistake they corrected the manufacturing process. There was a serial number break where the newer head was utilized. I Guess around 1994-95. They never revealed their mistake. The little testing I did on just one vehicle revealed the truck would resist starting once the IP reached 107 degrees. You could cool it off to 105 and it would just barely start.
So you might want to just replace the IP.
 

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Check your fuel cap. Open your cap and if you hear a large "Whoosh" sound then you have a restriction and need to modify your cap for better venting.
Even a small woosh sound is a problem. I discovered my cap is not quite right, but it doesn't make a large woosh. but is is stopped up enough to make a noticeable difference in power.
 
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thank you guys for all the help and information. Looks like im going to have to replace the IP shortly.
 

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Been there. After about 3 ip I learned the failure mode is the sensor that looks through a window to control timing I was told it could not be repaired. 3rd pump was a charm
 

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Sorry to be late for this thread, but I've been away for awhile. Thought I might just throw this out for the OP, because our engines are identical.
This truck had hard starting problems when hot also, and got to the point where it quit all together. The fuel shut-off solenoid in the IP was burned out. Once I found the culprit, and replaced it, the engine has run perfectly for about a year now. Not saying this is your problem, but easy enuff to investigate. Hope it helps, and you get it figured out.
 

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