03 supra launch injection problem

[buck337]

I have an 03 supra launch with an indmar 350 tbi. Under about 3\4 throttle the engine surges and hesitates, and under full throttle engine bogs down badly. A friend and i removed the spark arrestor and watched the injectors. When the engine surges, the left injector fires erratically and the right injector sprays fine. If we swap the connectors on the injectors the right side sprays erratically and the left side sprays fine. Under full throttle both injectors spray the same but dont seem to spray as much as they should under wot. The fuel filter has been replaced with no change in condition. Any help would be greatly appreciated. We also checked fuel pressure and it holds steady at 30 psi.

[DKJBama92Mariah]

Happy Holidays and welcome to the forum Buck.

I'm no expert of Indmar TBI systems but I'll do what I can and maybe one of the other members can chime in with more specific answers.

First, One question: When you tested the fuel pressure, did you test it at idle or while underway with the engine acting up? Having rock solid fuel pressure while under load with the engine acting up pretty much eliminates fuel flow as the potential cause. On the other hand, rock solid fuel pressure at idle tells us very little other than that the fuel pump is actually working.

Does the boat have a check engine light and if so, is it on?

It could also be going into "limp home" mode if it has one. I'm not sure if your model has one or not. Check the engine user manual that should have come with the boat. Does it work fine under 2k RPM?

[buck337]

The fuel pressure is steady at idle and all the way through the rpm range,even under load. The boat doesnt have a check engine light and all gauges shows no signs of problems.

[buck337]

Any one have any ideas?

[myturndad]

i had the same problem with my 05 ssv. turned out to be the fuel filter.

give that a try.

[buck337]

fuel filter is brand new. fuel has been drained and refilled with a fresh tank. any other ideas?

[Pdowling1]

According to your first post, the problem moves with the connection to the injectors. Sounds like the output of the ECM is bad. If the connectors look good, I'm afraid you need a new control module ($$$$$).

[buck337]

thats what im afraid of. i was just curious if anyone else has had this problem or had any other parts of the electronics to check before i invest that kind of money to repair.

[86Pirata454]

check for a bad ground or pinched wire before you put in a new ecm,

[DKJBama92Mariah]

According to your first post, the problem moves with the connection to the injectors. Sounds like the output of the ECM is bad. If the connectors look good, I'm afraid you need a new control module ($$$$$).

I'm afraid Pdowling is probably correct.

Like 86Pirata said, check the wiring for pinches or bad connections. Specifically tracing the wires from the injectors to the ECM. Check the ECM plug for corrosion on the pins.

If all of these look good, then it probably is time for a new ECM.

I'm not sure if it's the same system, but I knew a guy with a 98 Legacy with an Indmar 350 TBI. He had to get his computer replaced twice. Only one of those was under warranty.

[buck337]

I appreciate the responses. i'll check the grounds and the harness from ecm to injectors and post the results. thanks again guys.

[JUST-IN-TIME]

your best bet is to clean the grounds as said before and plug it into a computer and read all the sensors

[DKJBama92Mariah]

Welcome to the forum JIT! Always good to get a professional opinion around here. I was not aware that the TBI motors had a diagnostic port. The OP said he doesn't have a CEL, so I really dunno.

If he does have a diagnostic port, then yes, definitely, that should be his first stop. I was just running under the assumption there wasn't a port.

Admittedly, I'm no expert on marine EFI. My knowledge is just what I know from auto EFI systems. Personally, my #1 solution to EFI problems is to throw the ECM in the river and bolt on a Holley carb and Mallory distrubutor.

[mapleleaf]

DKJ, would it float???

[DKJBama92Mariah]

DKJ, would it float???

Depends on how hot they're running the nuke plant 30 miles upriver from me. :D

[mapleleaf]

I guess I could say the same about lake Ontario, I might have a 10 mile difference, yours'd probably float better!!!!

[buck337]

thanks for the replies guys. i found that the ground on the left side cylinder head in the rear had a lot of corrosion on the outer washer(looks like someone put a non-stainless washer on and it got a lot of corrosion on it). i removed the shift cable bracket and the ecm bracket,cleaned them and the ground stud. i also check all connections at all the sensors and at the ecm and they all looked fine. i will try it out this weekend and update the progress.