Help With Engine/Fuel Problems

[JusDreaming]

It is a Perkins 3 cylinder 18 hp engine, with inline injector pump
While in the Bahamas the engine began to smoke and run like crap. It is a blueish gray smoke indicates to me that it is unburnt fuel. So a good friend and I pulled the injectors and switched them with no change on #2. We did a compression test and it had 325, which is a bit low but in acceptable range. Next we would crack the fuel line and each one except #2 was a major change in RPM.
So now we are back in the states and had the injectors pop-tested and they basically all needed rebuilding. I picked them up installed them and the engine ran better, smoked less, but still smoking some. Now when I crack the #2 it effects the rpm, but very little. It seems to me that is now narrowed down to the injection pump. Also while in neutral it will rev up to 2400 rpm, but put it in gear and it will barely make it to 2000
SO that is the scenario and I am in need of input. It was suggested to check the output of each line coming out of pump. Or just accept that it is the pump and bite the 500-600 bullet

[Sandero]

I am no diesel mechanic.

I was told that when the rings are kaput you get blue smoke or dark smoke.

[bobconnie]

Mark the pumps position, remove it and have it cked out !! if bad fix or replace, theres really no way to tell on board with the tools you normaly have, just whats wrong you could have a mech come to the boat to ck the output there, but it will cost ya more !! have it cked is the only answer I can see the compression sounds ok for a cranking compression reading. Just my 2 cents after 50 + yrs of messin with diesels

[Astral Blue]

Originally Posted by JusDreaming

It is a Perkins 3 cylinder 18 hp engine, with inline injector pump
While in the Bahamas the engine began to smoke and run like crap. It is a blueish gray smoke indicates to me that it is unburnt fuel. So a good friend and I pulled the injectors and switched them with no change on #2. We did a compression test and it had 325, which is a bit low but in acceptable range. Next we would crack the fuel line and each one except #2 was a major change in RPM.
So now we are back in the states and had the injectors pop-tested and they basically all needed rebuilding. I picked them up installed them and the engine ran better, smoked less, but still smoking some. Now when I crack the #2 it effects the rpm, but very little. It seems to me that is now narrowed down to the injection pump. Also while in neutral it will rev up to 2400 rpm, but put it in gear and it will barely make it to 2000
SO that is the scenario and I am in need of input. It was suggested to check the output of each line coming out of pump. Or just accept that it is the pump and bite the 500-600 bullet

It is a good thing you ruled out the injectors, because it would be the first thing I would look at.

If a seal in your injector pump is broken and air is getting into the fuel, you will be getting smoke. Also, if the seal between the injector pump and the crank case is compromised, oil can enter the pump or fuel can enter the crankcase. If oil from the crankcase gets into the flow of fuel, you will see blue smoke.

Here is an easy way to tell whether there is a compromise in the seals. Connect a clear hose to your injector pump's fuel return port and run the hose to a bucket. Start the engine and observe the flow of fuel through the return line. If you see bubbles, air is getting into the fuel. If there is any discoloration of the fuel, crankcase oil is present.

That is going to be the easiest and most cost effective way to determine whether a seal has been compromised. If that's the case, you can get the pump resealed for a fraction of the cost of a full scale rebuild.

Hope this helps...

[JusDreaming]

if it was a bad seal wouldn' it effect all cylinders? The pump people said it is possible to just lose on cylinder due to a spring or diaphram failure

[propnut]

When injectors gum up is usually from bad fuel the same fuel that runs thru the pump
the pump could not doubt use a overhaul but i fear you are going to have to address the difference in compression as well or its going to be a partial fix
a leakage test should be done to confirm where the leakage is
a leak tester puts compressed air into the cylinders and measures the % of leakage you will be able to hear where it is leaking thru the crankcase vent means bad rings out the intake means bad intake valve ect .
likely the pump will not fix the problem if its a rotatory pump that most Perkins engines use but there are a couple components in there that can effect only one cylinder its worth a shot and probably needs to be done any way

[JusDreaming]

FYI the engine has 5k+ hrs on it.

[Astral Blue]

If the engine has 5K hours, the pump is due for a rebuild. I agree with propnut in that while there are factors in the pump that can affect one cylinder, getting it rebuilt might be a partial fix. Conversely, addressing an issue with the cylinder rings and not addressing the pump is going to be a partial fix as well.

Rebuilding the pump is not going to result in better compression readings. However, you will have eliminated a significant contributing factor to your problem. Do perform the test I mentioned previously.

If you are at 5K hours, it might be a good idea to consider giving the engine an overhaul anyway. While 5K hours is somewhat premature for most Perkins engines, failures are entirely dependent on how and under what types of conditions the engine was used.

[JusDreaming]

@ Astral is the seal something that can be replaced or is it just part of a rebuild? Would or could it affect just one cylinder? When I crack the fuel line to #2 it looks to me, Shade tree novice, that I am getting air mixed with the fuel.
And could it have been caused by double lightning strikes which exited through the engine/shaft

[sailinman]

if all the cylinders except #2 are ok, then it isnt a pump issue... the pump would affect all cylinders

did you do a valve adjustment... I would do that first, or at least verify the gaps, then I would jump to the injectors inspection/rebuild...

good luck

[Astral Blue]

Originally Posted by JusDreaming

@ Astral is the seal something that can be replaced or is it just part of a rebuild?

Resealing an injector pump is not a do-it-yourself project. It requires special tools and a means to bench test it to ensure the seal is effective.

You might considering giving the guys at Diesel Fuel Injection Service in Portland, OR a call. They are equipped to diagnose and repair just about any injector pump on the market and have incredibly fast turnaround times as well as very reasonable pricing. I have used them several times (for three different injector pumps) and have very good experiences with them.

[JusDreaming]

well when the mechanic pulled the pump, the #2 pump cylinder fell apart in his hand. And after having it rebuilt,( in one day), and re-installed it is now running well and no smoke
Thanks every body for the input!!!!!!!!