WOT issue non-stang

[duststang]

1999 5.7 Penta boat WOT issue
Just purchased this boat (99 5.7 Penta TBI) took it out ran good no issues, full throttle over 5000RPM. This weekend took it out and at WOT it bogs and cannot get past 4200RPM's. I can run it at 4200RPM's 7/8 throttle with no problems (I ran it 4200 for 30 mins) but soon as I WOT it bogs? Take off WOT it will bog if I ease up just a little it will take off. The boat starts ok cranks for a couple sec and starts, idles good smooth. When I take the boat out of the water there is black soot on the back like it is running rich? I am now wondering if it could be bad fuel, water in fuel or should I just start throwing parts at it? The motor is a Chevy 350 TBI even though it is a boat motor. Anyone ever had similar issue car truck or boat?

[sean]

Sounds rich.

[thecollector]

Check fuel pressure and do a sweep of the tp with a meter. Does this have stand alone management or is there a gm OBD I port on it? Does the fuel smell turned? How old is it(fuel)? Try removing the cowl and enriching it with fuel past your 7/8 point. Is this only under load will it free rev past the 7/8 point?

[duststang]

Check fuel pressure and do a sweep of the tp with a meter. Does this have stand alone management or is there a gm OBD I port on it? Does the fuel smell turned? How old is it(fuel)? Try removing the cowl and enriching it with fuel past your 7/8 point. Is this only under load will it free rev past the 7/8 point?

will try this out tonight... thanks

[duststang]

replaced dist cap, rotor, fuel filter, air breather, and plugs. Put Seafoam in gas then took it out yesterday and it still bogs WOT. I noticed all the plugs had a lot of gas and #3 was more black than the rest. The back of the boat still had black on it like it is running rich. Is it common for a TBI to get gum up?

[jktruckin06]

Something with timing/advance maybe?

[4n_eatr]

If its TBI on a Chevy with the two big injectors in the TB that looks like a carb, those injectors are known for going bad. I forget how to test them though.

[duststang]

Yes it is a TBI with 2 injectors on the top. Anyone know of how to check them? I was thinking maybe the TBI is gum up? can you rebuild these?

[4n_eatr]

You used to be able to rebuild them but it might be cheaper now to buy new ones. Ill have to look and see how to test them. It's been a while.

[duststang]

Here are some helpful video's incase someone might have similiar issues..
http://www.youtube.com/watch?v=_HLCid1Sh6M
http://www.youtube.com/watch?v=TDbRw-xEtyI
http://www.youtube.com/watch?v=5A4a5OOGqPo&noredirect=1

[duststang]

ok so I have replaced the temp sensor and took the TBI apart and cleaned all new gaskets. I put new screens and orings on the injectors. they seem to have a good pattern both working (not squirting or dripping). I bought a map and temp sensor from Orielly's cross ref. Now the boat is running really rich black plugs idle worse and still bogs on take off. Once on plan I can full throttle with no issues. Its not pinging on top not sure how to set timing yet. it is so rich that within on 10 mins of running the plugs are black.

here is a short video of it at idle you can see the injectors working and the RPM is about 700.
http://www.youtube.com/watch?v=3ahokath08o&feature=em-share_video_user

[duststang]

well found out that blew head gasket between 3-5 and #3 exhaust valve is bad. It looks like the guy I purchased the boat from over heated it. I should have it back together this weekend and hope to be on the water.