Fuel Injector Question

[Tri County Trail]

Looking for opinions anyone think this injector was leaking cylinder compress on that cylinder.
Pintel cap was missing on removal but oring was found in manifold. Engine was low on power checked plugs wires fuel pressure reg for paint all good. Compression test is next once injectors are back. Rethinking maybe I had a compression leak in the number 4 cylinder where the Pintel cap was missing and maybe leaking thru that o-ring.


"Your set of eight Delphi injectors flow tested 'okay' right out
of the box ( after an initial exterior cleaning / de-greasing ), and
flow tested at about a 5 % flow balance ( 78 to 82 cc ). An 5 % flow
balance is not great for a used set of injectors, should be a little
better. Spray patterns were normal in all of the injectors. All of the
injectors held pressure ( no leaks ).
The engine would have run okay with these injectors, maybe a tiny
bit rough.
Will have them in the ultrasonic tank and finished tomorrow
morning. Should get a little better after cleaning."

First pic showing cylinder blowby
second pic is what all other injectors looked like.
Never heard anything noise wise but twin 496s and hatch was not open at cruise.
looking for thoughts.

 

[ttmott]

Any cylinder leakage past the intake valve that significant would cause the engine to run very badly. The MAP sensor would cause an extreme over-fuel condition and pretty much drown the dog. That looks to be an intake valve major failure.

 

[scoflaw]

Agree, the cap came off and damaged your intake valve.

 

[Tri County Trail]

Any cylinder leakage past the intake valve that significant would cause the engine to run very badly. The MAP sensor would cause an extreme over-fuel condition and pretty much drown the dog. That looks to be an intake valve major failure.

The injector port is in the manifold couldn't it be leaking air into the intake manifold the engine ran good except at wot only got to 4400 rpm and seamed to lack power other engine (also needed more throttle at cruise) to 5000 rpm and strong.
Engine used more fuel so I agree with you I'm NOT saying it was leaking at valve BUT intake port past oring on injector to the outside of the manifold it could leak both ways depending on the engine rpm ect. what ever was leaked would not have shown up on the map sensor pressure.

 

[Tri County Trail]

Agree, the cap came off and damaged your intake valve.

I will be checking with scope hopefully will not have to pull head. It has been like this since I bought it last september. New to me boat headaches.

 

[scoflaw]

Injector has nothing to do with compression, do your test with the rail off now.

 

[ttmott]

The injector port is in the manifold couldn't it be leaking air into the intake manifold the engine ran good except at wot only got to 4400 rpm and seamed to lack power other engine (also needed more throttle at cruise) to 5000 rpm and strong.
Engine used more fuel so I agree with you I'm NOT saying it was leaking at valve BUT intake port past oring on injector to the outside of the manifold it could leak both ways depending on the engine rpm ect. what ever was leaked would not have shown up on the map sensor pressure.

The intake plenum and runners are typically at vacuum pressures (unless, of course, it is supercharged). If the intake valve was damaged enough to allow cylinder pressures and temperatures back into the manifold runners things will get damaged.

 

[Espos4]

Look for heat damage on you fuel injector caps. If any are melted, that’s a leaky intake valve allowing combustion gases back into the intake manifold, melting the cap on that particular injector.

 

[Tri County Trail]

Look for heat damage on you fuel injector caps. If any are melted, that’s a leaky intake valve allowing combustion gases back into the intake manifold, melting the cap on that particular injector.

No damage on any other caps except for the missing one. I will check the comp on that one first. Thanks

 

[Tri County Trail]

Injector has nothing to do with compression, do your test with the rail off now.

I have everything lose and wiring harness off I will wait till I get injectors back but will look at back side of valves thru injector port.

 

[scoflaw]

Why wait? Test will reveal more than a look. I'll bet the head's coming off.

 

[Tri County Trail]

Found the Pintel cap on top of intake on cylinder #4 got it out wonder how long its been off?

 

[Tri County Trail]

Got injectors back flow tested fine, reinstalled on rail now to get the back in boat for test. Also ohmed out injectors to harness.

 

[scoflaw]

Found the Pintel cap on top of intake on cylinder #4 got it out wonder how long its been off?
View attachment 134507

Probably long enough to damage the valve and seat. Had a similar thing on a generator, the valve didn't open enough to let the nut drop through but tore up the seat and valve pretty good.

 

[sejensen737]

I had same issue with an injector missing pintel cap. Cylinder 7. Discovered while chasing starting/running problems. Also mis-seated o-ring. I never thought to go looking for the cap as I assumed it just got mashed and swallowed up as they seem to be made of a plastic/nylon material. Engine runs fine through rpm range. Maybe I got lucky...
Does anyone know exactly what those pintel caps are there for?

 

[sejensen737]

google's my friend...page 4 if interested...

Ttt37 (tomco-inc.com)

 

[Tri County Trail]

Probably long enough to damage the valve and seat. Had a similar thing on a generator, the valve didn't open enough to let the nut drop through but tore up the seat and valve pretty good.

When I pulled it out it looked fine didn't see any damage I will test run it and if I still have issues I will do a compression test.