Sorry if there is already a thread about this, but i'm wondering if any of you can help me. I have a gtr 37 efi. It runs good usually, but yesterday morning around 4 am i left from the launch and when I would pull the throttle it was like it the engine was catching or turning up enough to push the prop, After a minute I revved the engine and slowly pull the throttle and it caught and ran good the rest of the day. This morning when I launched my boat it did it again but it took alot longer for it to catch and me to get to the blind because a couple of times I'd take off and then it would do it again. I picked the prop out of the water and revved it up and it spun good until I put it in the water. Reverse seems to work fine when this is happening. Its almost like only in forward that the engine is turning the prop when out of the water, but not when it is submerged in water. After I made it to the blind, I check the filters and oil and things like that. When I left it did the same for a second and then took off and ran like a charm the whole way in which is about 45 minutes. The engine never kills or sounds really bad, Just at first when I go in the morning to take off its giving me trouble to get going. Any ideas on what this could be? I just had the wiring harnesses on the efi changed twice, and from what its doing, i dont really think its that.

Efi is supposed to solve that issue.

Is the engine running poor, or is the clutch slipping?

"Get an EFI" they said
"It'll be better than carb'ed" they said

Less of a load on the engine in reverse than in forward is why it appears to be ok in reverse? Sounds normal but just doesn't have the power but wakes up and runs fine after it warms up?

It's supposed to add more fuel until it warms up, similar to a carb being choked but for some reason I'm thinking a faulty O2 sensor.

^^ wow ^^

Will is just making sure you are paying attention

I'm going to put money on you need to get the engine checked out man. First thing I would do is get it to your nearest service center.
I personally would check valve lash, and then check fuel connections for air leakage. Next move onto know wire harness issues and check for those and repair as necessary.
You as a consumer shouldn't have to touch it. It has a warranty let briggs pay the problem.

You are seeing loos of performance in forward as that is the MOST load on the engine. Neutral has virtually 0 load on the motor, Revers is geared VERY low so that doesn't put much load on the engine aswell. You more than likely have intermittent fuel delivery problems.

If it were valve lash, it wouldn't matter if it was cold or warm. The key here is after it warms up, it runs fine... now what parts in an EFI system are temperature related?

Check the coolant sensor. It's next to the O2 sensor.

I'm talking about the engine temperature, cold versus normal operating temperature not the damn outside air temperature.

Some shouldn't ask for advice. And some shouldn't give advice. Dumb and dumber.

You saying nobody can ask a question that might lead to an answer?

I will get back to you. when I find my O2 sensor

Haha

Make sure your map sensor at the intake is plugged in. And if it is do you have a volt ohm meter.

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when it acts up like that put your finger CLOSE to the exhaust header on each head. if its running on one cyl or worse on one cylinder one side will be noticeably cooler and it may even let you touch it!.. if your lucky. but my guess is its running too lean for a little bit.. too bad a little code does't flash that says map sensor low voltage.. i mean this is 2016 they've only had 30 years to catch up with this efi stuff