4.3 EFI trouble

[Monkey Business]

My 2001 4.3's are not been behaving.

Initially my port engine kept dying and would not restart. I replaced the anti-siphon valve as it looked very corroded. Good to have it replaced, but didn't fix symptoms. I then swapped IAC from starbord to port and motor started. Starbord would not start with the port side IAC in it.

Yesterday I received the new IAC's in the mail and replaced both. Both engine startup fine now and the starboard is running strong. However, the port side still isn't perfect. When I put the motor in gear and push the accelerator
down it will climb to about 1500-1800 and start bogging down until it max out at 2100 and have fuel fumes coming out. If I slowly move it forward it will build up RPM and have power. Basically it boggs down with any really acceleration unless it is really slow and deliberate.

I watched the injectors running both motors and no noticable differences.

I am thinking the next step should be replacing either the TPS or shift interruptor switch. I am going back down to the boat tomorrow and will try swapping these parts from the starbord to the port.

Are there any other ideas?:huh:
Thanks

 

[SR Tech]

I'd start at the basics

-When was your last tune up?
-When did you change your fuel filter

If you can see unburnt fuel coming out of the exhaust, chances are its going to be a spark related.

Combustion mixture isn't being fully ignited and getting pushed right out the exhaust.

 

[Monkey Business]

Thank you for the reply, I do appreciate it. I just purchased the boat in August, so I am going through all the basics and getting to know my engines. I am not sure when the last tuneup was, but I think you are spot on.

Sunday, I went down to the boat and the port side would not start at all just kept turning over and it sounded like it wanted to catch but just wouldn't regardless of throttle position. I started by swapping the tps sensors from the starboard motor...not effect. I didn't switch the shift interuptor switch, just inspected it. No real corrosion or obvious signs of detioration. Next I moved to the distributor and followed to the coil. The coild wire was in horrible shape. At the distributor side the connection was clean and easily unplugged/plugged in. However, on the coil the boot just pull off the connecter and the wire itself was kind of gummy. This goes back to your point of the spark...bad coil or coil connecting should cause week sparks or no spark...running rich. I think this adds up. So I ordered two coils and a shift interuptor switch just incase. Diagrams show just a single bolt that needs to be loosened to lift the coil out. The only wires I saw on the coil was the one from the distributor. Should anything else be connected to it?

I plan to do a full tune up in the spring or over the winter. I just need the boat to run now so I can bring the fuel level down some and get her up on the trailer.

 

[Monkey Business]

I think I am definitely at my wits end.

So far, I have replaced IAC, TPS, coil, wire set, cap, rotor, and plugs. Everything minus the TPS looked like they should be replaced so I don't feel like I have wasted money yet.

However, problem is still there. Engines smell like they are burning rich (old spark plugs had oil on the threads but the tips were dry and looked fuel fouled), they idle evenly, but any acceleration causes them to hesitate, bog down and die if i don't bring them to neutral quick enough.

When I get the boat back to California I am going to have a tech take a look, but until them I'm stuck.

So any ideas would be appreciated and any experience with any shops in the Newport Beach area would be great too. I already had one bad experience with a local marine shop here in alabama...hoping not to have a similar one. Thanks.

 

[SR Tech]

How old is the fuel in the tanks?? When did you change the filter??
You've pretty much replaced everything ignition wise that could be the problem so really the only thing left is bad gas, or bad compression.

Try using some mercruiser dri-fuel, or any dry gas for that matter.

And try testing the TPS with a probe and volt meter. Should be 4.5v on the signal line at WOT, and around .5v throttle closed. You can do this with just the key on and moving the throttle cable manually