3GM30F Service Issue

[skunther]

I had my high pressure pump and injectors serviced at.

https://www.seattleinjector.com/

Can anyone tell me what shops service injectors and injector pumps in the Bellingham area?

 

[Scott T-Bird]

The shop reused the same shims that were there before the pump was rebuilt. They said the timing should therefore be the same. Would rebuilding the pump necessitate re-setting the timing from scratch? Or should reusing the same shims be fine? The shop said when pumps are removed and replaced It is typically not necessary to adjust the shims once timing has been set initially.

The tech did mention to me that a rebuilt injector pump can interact with cylinders differently than before, and that I possibly could have had a situation in which the pre-rebuild injector pump was somehow interacting better with the low compression cylinders than the rebuilt injector pump is, resulting in poor starting. Does this make sense? I have a hard time wrapping my mind around this one. It doesn’t make sense to me that fixing a poorly running injector pump would cause the cylinders to suddenly fire improperly at startup.

Based on the assumption that they didn't disturb the timing shims, I suspect they aren't the problem. I think that if you know that you have low compression, any explanation for poor starting boils down to this fact. There is probably no sense in trying to make any sense of the before and after when you know that you still have a problem that stems from low compression. If you are trying to get back to square one you haven't gained anything. At this point, I would be focused on rebuilding the engine to get all cylinders firing, so to speak. Focus on the compression problem.

 

[jssailem]

I hear Northland Diesel has been in the business since the late 60’s. No personal experience with them.

 

[Mark Maulden]

I hear Northland Diesel has been in the business since the late 60’s. No personal experience with them.

They’ve always treated well. They checked my injectors and fixed a leaky injector and didn’t charge me…

 

[Mark Maulden]

Based on the assumption that they didn't disturb the timing shims, I suspect they aren't the problem. I think that if you know that you have low compression, any explanation for poor starting boils down to this fact. There is probably no sense in trying to make any sense of the before and after when you know that you still have a problem that stems from low compression. If you are trying to get back to square one you haven't gained anything. At this point, I would be focused on rebuilding the engine to get all cylinders firing, so to speak. Focus on the compression problem.

The injector pump is a conglomeration of separate pumps. One for each cylinder. If during a rebuild, the stroke of these pumps is changed, the engine should be retimed. Years ago, going through this with my green machine, the mechanic stated he has seen multiple engines of the same brand/model use different shims. It’s an individuality trait..

 

[skunther]

The injector pump is a conglomeration of separate pumps. One for each cylinder. If during a rebuild, the stroke of these pumps is changed, the engine should be retimed. Years ago, going through this with my green machine, the mechanic stated he has seen multiple engines of the same brand/model use different shims. It’s an individuality trait..

Is it possible that bad timing due to the rebuild could cause the engine to start terribly but run well once started, and adjusting the timing would address the starting issue without compromising the “running well” part?

 

[marcham]

Yes, but it could be an installation issue, not necessarily a rebuild issue. I would have a mechanic go through section 2.7 of the service manual....

 

[skunther]

The engine would only after a very light burst of Thrust in the air intake, but then ran well yesterday once started. I cruised at 2700rpm for roughly 1.5 hours before anchoring. This morning was the same hard start issue. It wouldn’t start after 15 seconds of cranking, and there was grey smoke from the exhaust. This is unburnt fuel, no? Previous to work, it would start up immediately in these circumstances.
The shop is sending a tech to check the pump, timing and injectors this next week. I haven’t wanted to touch these systems as long as they are working on them.
Is it likely possible air is leaking into the system causing the hard start? Would the engine still run as well as it has when cruising if air is entering the system? I replaced the fuel filters when the engine was apart, but I have changed them before without any issues. Is it possible to confirm if air is being sucked into the system somewhere?

 

[kappykaplan]

Would the engine still run as well as it has when cruising if air is entering the system?

No.

 

[MitchM]

OP do you have an itemized bill listing parts costs for the [parts installed ? are the notorious copper washers included? copper washers on Yans need to be annealed or they develop leaks. new washers are cheap.

 

[jssailem]

This is unburnt fuel, no?

Yes. More white than grey is the smoke.
I know it well. My rebuilt engine has been a bit slow to start when cold. Once it fires, there is a puff of dark smoke, then she runs smoothly. Another hint is the small bit of sheen on the water behind the exhaust. Unburnt fuel is being expelled. If I stop the engine and then restart it there is no delay. It fires right up.

I think your decision is smart. I would let the mechanic resolve the issue. You paid them to complete the work.

 

[skunther]

OP do you have an itemized bill listing parts costs for the [parts installed ? are the notorious copper washers included? copper washers on Yans need to be annealed or they develop leaks. new washers are cheap.

I do not. I have not been billed yet. I assume new parts were used (compression washers etc) as it is a reputable company. I do not know for certain though.

 

[skunther]

No.

So if the engine runs well while cruising, then air is not entering the system causing the hard start?

 

[kappykaplan]

So if the engine runs well while cruising, then air is not entering the system causing the hard start?

Not likely.

 

[skunther]

Not likely.

What could be the cause the hard start after work performed on the injector pump and injectors then? Timing, as @marcham proposed?

 

[kappykaplan]

If you have air entering the system while starting, you will have air entering the system while cruising, perhaps more than when starting.

 

[jssailem]

Timing, as @marcham proposed?

Most likely.

 

[skunther]

Could there be a vacuum leak elsewhere in the fuel system? Or would that be essentially the same thing?

 

[jssailem]

A vacuum leak in the fuel system would draw in air to the fuel lines. This would be a power problem all the time. The High pressure pump would not have enough fuel to feed the injectors when running. You would not see the white smoke. You would see no smoke. Likely never start.

The white smoke indicates fuel in the cylinders but not enough compression to ignite the fuel air mixture. You run the engine and the compression improves. Then it fires off and you get white and then black smoke. When the engine warms you get a smooth running engine.

What happens when you have run the engine up to running temp (165-180º F) and then shut the engine down. Will it restart smoothly?

 

[skunther]

A vacuum leak in the fuel system would draw in air to the fuel lines. This would be a power problem all the time. The High pressure pump would not have enough fuel to feed the injectors when running. You would not see the white smoke. You would see no smoke. Likely never start.

The white smoke indicates fuel in the cylinders but not enough compression to ignite the fuel air mixture. You run the engine and the compression improves. Then it fires off and you get white and then black smoke. When the engine warms you get a smooth running engine.

What happens when you have run the engine up to running temp (165-180º F) and then shut the engine down. Will it restart smoothly?

It restarts immediately at idle. No problem.