WOT woes... comp test results

[dkellogg3]

So, I've been battling WOT problem.... at Chris' suggestion i interrupted fuel sys checks to run a comp test

1994 4.3lx

Results:
1...170
2...175
3...170
4...165
5...175
6...179

Numbers look fine.

Spark plugs...


Port (1,3,5) dark sooty
SB (2,4,6) light sooty

Any conclusions from this?

Back to fuel system...

 

[greg82255]

Re: WOT woes... comp test results

So, I've been battling WOT problem.... at Chris' suggestion i interrupted fuel sys checks to run a comp test

1994 4.3lx

Results:
1...170
2...175
3...170
4...165
5...175
6...179

Numbers look fine.

Spark plugs...
View attachment 159698

Port (1,3,5) dark sooty
SB (2,4,6) light sooty

Any conclusions from this?

Back to fuel system...

Take a look here - go through each test and you should find your problem.

http://forums.iboats.com/showthread.php?t=295070

 

[Failproof]

Re: WOT woes... comp test results

Carbed or fuel injected? Its probably already been said in the other thread but i didnt follow that one.

 

[dkellogg3]

Re: WOT woes... comp test results

Carc. Recently reolaced weber 4 w/ edelbrock. Low wot was the reason for the new carb.

 

[Bondo]

Re: WOT woes... comp test results

Ayuh,.... Have ya methodically gone down through Don's list of possible causes for this, listed in the Adults Only section,..??

 

[dkellogg3]

Re: WOT woes... comp test results

I am going through the list, and have eliminated all but:

4. Crankcase oil volume, high oil level can cause aerated oil and lifter collapse
I noted the the oil level was a little high yesterday. Maybe 1/8" to 3/16" above the "high" mark. Didn't think that was too high, but...

8. Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive

11. Fuel pump pressure and vacuum
Did fuel system test yesterday. Hooked the rig up between air/water separator and pump. At idle, air bubble remained right after the separator. Took her out and brought her up to just below where she stumbles (2500rpm) and cruised for a bit. Couldn't get rid of the bubble, and with that in the line, was unable to get any vacuum readings.

Does the fact that all 3 plugs from the port side have dark soot, and all three from the starboard side have light soot mean anything?

THanks,
Don

 

[sharkin95]

Re: WOT woes... comp test results

The compression is very good for a 1994. I would say this is a carburetor issue. try rejetting the #1409 edelbrock, it seems you are getting an over rich issue. My Weber has .089 prim with .089 sec. and 68x57 rods with a 4" hg yellow spring. The #1409 has .098 prim and .101 sec with 68x47 rods and 6" hg orange spring, for my 2 cents this setup is for a v8 not a v6.

 

[Bondo]

Re: WOT woes... comp test results

Does the fact that all 3 plugs from the port side have dark soot, and all three from the starboard side have light soot mean anything?

Ayuh,.... That would lead me to believe, 1 side of the carb is richer than the other....

With a dual plane manifold, each side of the carb, feeds the opposite side of the motor....

 

[dkellogg3]

Re: WOT woes... comp test results

I was very happy with the compression test. I actually was avoiding it because I was nervous about it, but was relieved with the results. I installed the Edelbrock 1485 kit in the carb during the install. The low WOT was occuring before the carb swap, so I'm thinking although I might need some fine tuning with the Edelbrock, I'm don't think it's the root of my problems. Based on fuel test, I'm finding it odd that I can't pull the bubble out of the supply line.

I'm thinking a new pump is in order.... BUT.... does a restricted exhaust happen often enough that I should look at that first?

Thanks...

 

[sharkin95]

Re: WOT woes... comp test results

it doesn't, but to rule that out I would check the flappers in the exhaust pipe anyway usually you would get a temp increase because of the blockage. a new fuel pump runs about $150.00, did you check the anti syphon and clear the vent?