2001 Maxum 2900 SCR 7.4L STOPPED PLANING OUT!

[NautiGal]

Boat/purchase history: 2001 Maxum 2900 SCR 7.4L MPI 454 w/Bravo 3. Found the boat online through local dealer this past January and loved everything about it so went to take a look. She was immaculate and has every bell & whistle you could ask for! 300 hours on engine & 1500 on Westerbeke generator (older couple bought her from same dealer 8 yrs prior and used her primarily to cove out on wknds. Selling her so they could travel to see grandkids more). Always freshwater kept. Opened the engine compartment & immediately noticed thick black liquid in bottom of it…not water with a film over it. Broker tried to tell me that was normal – I knew better & said so. Still very interested in boat so proceeded to set up survey/sea trial. Morning of survey they have her up on a trailer to check hull, lower unit, etc. Broker says to try & stop my surveyor if possible because he had some problems getting her up to speed – idle was fine but bogging under power. Surveyor already on way so he did the out of water check which was all good. We also pulled quite a few zebra mussels off lower unit. Local dealer shop determined the fluid in engine compartment was gear lube from broken seal in lower unit (confirmed what surveyor suspected) so owner agreed to repair that, replace faulty thermostat, and replace spark plugs, etc(basically a mini tune-up). Went for sea trial following wknd. Surveyor was out of town for 2-3 wks so took my marina mechanic who is also married to old friend of mine. She planed out/sea trialed beautifully! We ran her for half hour with no problems whatsoever. He noticed slight starter drag while starting and perhaps small leak in riser but nothing that would be a deal breaker. Pulled trigger following week(mid-Feb) then had to wait a month to have her transported to my lake/slip (beam too wide for us to legally tow without permit). My mechanic met us upon arrival at ramp so he could inspect lower unit, bellows, bottom job, etc. since he didn’t get to see during sea trial – all looked good. Noticed center lights of transport guy’s trailer were busted – he said my broker pulled the boat up a little too far on trailer that morning & lower unit broke the light cover but everything looked/worked fine. We launched, she started right up, ran well, planed off and I managed to back her into my slip on second try! =)

When problems began: Weather went south so couldn’t run her for a few weekends but when I was able to she planed out & ran fine - although I had a heck of a time getting her started and she died under idle a few times. We assumed due to starter drag, half tank of old gas & lack of use so mechanic suggested I add a bottle of Techron Fuel Cleaner (said he’s had better luck with Techron than SeaFoam) and RUN HER! He said running her is the best thing I can do for her since we really have no idea how long she sat or how long that gas had been in her. Fast forward a few more weeks to late April/early May and the starting/dying problems are resolved, she has new gas and things are improving BUT then one day she wouldn’t plane out. Could only get 3900 rpms and 10 mph out of her – UGH! Had passengers get in cabin which made her plane. Mechanic takes her for a spin, notices a rhythmic miss and thinks bad spark plug/cylinder creating power loss. Opens her up to diagnose which plug and says it didn’t look like the spark plugs had recently been changed like they were supposed to have been by dealer so he slaps a whole new set in. Still won’t plane 95% of time! The only two times she planed after this were after I slept on the hook - she didn’t plane on the way to sleep cove but she did plane out when I was driving her back to marina the next morning. Go figure?! Now he’s thinking maybe dirty fuel injectors so we add Techron Injector Cleaner and keep running her (he says I’m not hurting anything else by running her). Tried new plug wires with no luck. She won’t even plane when I’m solo now OR when I put people in cabin bow. Last test run he was been able to get her up to about 4100 rpm using some little tricks he knows but still not planing and he says she should plane around 3500 - 3800. Oh yea, we shut it down to jump in water to cool off and when he went to start her the dang ignition switch broke so now that has to be replaced. UGH!!! I asked if we need to do a compression test - he says no because she’s idling smooth, all gauges reading fine, etc. He is running out of options to check in ignition system. Now he’s wondering if it’s prop or lower unit related instead of/in addition to fuel injectors. Really hate to spend a few thousand on new injectors only to find out that’s NOT the problem! Btw, trim tabs and trim are working fine. Any suggestions as to what it might be or what tests he can do to diagnose it? At my wit’s end!

[mmwjr]

Darn my attention span is not that long lady :-)

Ok remove spin on fuel filter and pour the contents into a glass jar, is the gas a nice golden color? Any debris?

Next the engine has a mechanical fuel pump mounted to the raw water pump, there is a oil section on the water pump that is over looked in maintance to ensure its got oil in it and the result is a warn arm on the fuel pump which then results in low fuel pressure starving the engine.

Just two ideas that I would start with, these are also very common issues I have seen.

[NautiGal]

LOL Mike! Sorry for the novel but wanted to give the FULL history in case there was some little detail that might be the Ah-ha! moment for someone. I will pass your feedback along to my mechanic. Thanks so much!

[cdhunter]

Has any one tried connecting a scanner to the engine while underway? I had a 99 2800 SCR with 7.4L MPI and my mechanic hooked a scanner up to check various engine statistics and look for error codes. His scanner could even determine how many gallons the engine was burning per hour.

[mmwjr]

Originally Posted by NautiGal

LOL Mike! Sorry for the novel but wanted to give the FULL history in case there was some little detail that might be the Ah-ha! moment for someone. I will pass your feedback along to my mechanic. Thanks so much!

Re-read, well skimmed through your initial post again. Being that it has low hours and had fuel issues there may still be gunk in the tank clogging the pickup screen. Add this to the list before even considering replacing injectors.

If proped wrong the max rpm would be constant and not change from one trip to the next.

[shrew]

How are the temps? Having a little leak in the manifolds and risers is like having a little leak under your kitchen sink. It should not leak at all, is indicating a problem and will get worse over time. For example, if it's leaking out, how do you know it's not leaking IN?

[mmwjr]

Originally Posted by shrew

How are the temps? Having a little leak in the manifolds and risers is like having a little leak under your kitchen sink. It should not leak at all, is indicating a problem and will get worse over time. For example, if it's leaking out, how do you know it's not leaking IN?

And leaking IN can lead to needing a new engine.

[NautiGal]

Originally Posted by cdhunter

Has any one tried connecting a scanner to the engine while underway? I had a 99 2800 SCR with 7.4L MPI and my mechanic hooked a scanner up to check various engine statistics and look for error codes. His scanner could even determine how many gallons the engine was burning per hour.

Mechanic says she's not throwing any codes which is why it's taking him a while to figure it out. A friend's husband who is well versed in automotive engines says that's a pretty clear sign it's fuel related or possibly a bad sensor. Agree or disagree?

[NautiGal]

Originally Posted by mmwjr

Re-read, well skimmed through your initial post again. Being that it has low hours and had fuel issues there may still be gunk in the tank clogging the pickup screen. Add this to the list before even considering replacing injectors.

If proped wrong the max rpm would be constant and not change from one trip to the next.

Shorter posts in future I promise Mike! (LOL)
What you say on props make perfect sense so should be able to rule that out.
I will definitely run the pickup screen by him. Replacing injectors will be last resort. I hear from an automotive mechanic that there is a test that can be done to see if injectors are bad...he says essentially anything electrical can be tested but admittedly he doesn't know boats at all. Thoughts?

[NautiGal]

Originally Posted by shrew

How are the temps? Having a little leak in the manifolds and risers is like having a little leak under your kitchen sink. It should not leak at all, is indicating a problem and will get worse over time. For example, if it's leaking out, how do you know it's not leaking IN?

No overheating - temp rides right at or just under 175. All gauges reading normal.

[NautiGal]

Originally Posted by mmwjr

And leaking IN can lead to needing a new engine.

DEFINITELY don't want that!!! Will make sure he checks/watches that.

[cdhunter]

Originally Posted by NautiGal

Mechanic says she's not throwing any codes which is why it's taking him a while to figure it out. A friend's husband who is well versed in automotive engines says that's a pretty clear sign it's fuel related or possibly a bad sensor. Agree or disagree?

I am no expert, but it could be a fuel issue. Has anyone checked the fuel pressure at the fuel rail?

[mmwjr]

Originally Posted by NautiGal

Mechanic says she's not throwing any codes which is why it's taking him a while to figure it out. A friend's husband who is well versed in automotive engines says that's a pretty clear sign it's fuel related or possibly a bad sensor. Agree or disagree?

A bad sensor should show up in a fault code. I'm thinking a fuel related issue.

[mmwjr]

Originally Posted by NautiGal

Shorter posts in future I promise Mike! (LOL)
What you say on props make perfect sense so should be able to rule that out.
I will definitely run the pickup screen by him. Replacing injectors will be last resort. I hear from an automotive mechanic that there is a test that can be done to see if injectors are bad...he says essentially anything electrical can be tested but admittedly he doesn't know boats at all. Thoughts?

It's not the electrical part of the injector that typically goes bad but the mechanical side such as the seat not sealing causing them to drip but the result would not be what you are seeing. They could also be dirty and sputtering, this can be cleaned but again your issue does not suggest this IMO.

[mmwjr]

Originally Posted by cdhunter

I am no expert, but it could be a fuel issue. Has anyone checked the fuel pressure at the fuel rail?

I agree 100%.

[mmwjr]

I know you said the spark plugs were replaced but what about the distributor cap, rotor, spark plug wires. Does the loss of rpm only happen when the engine is warm? If so the ignition coil may be breaking down.

[cdhunter]

Originally Posted by mmwjr

I know you said the spark plugs were replaced but what about the distributor cap, rotor, spark plug wires. Does the loss of rpm only happen when the engine is warm? If so the ignition coil may be breaking down.

Definite possibility that I did not consider. I once had a truck that ran fine when it was cold but one it warmed up it did not have enough power to go down the road above idle RPM, but would rev fine in neutral. Let it sit for a couple or hours and it was fine. The issue was the ignition coil.

[dave4boats]

You could have mechanic hook up a small remote fuel tank to see if boat runs better. I just did this for a friend and boat ran great. So I drained his tank on boat and out of 35 gallons i got about 12 gallons of water. One can of seafoam and 15 gallons of high test boat back to normal. He has had issues for about two years, found o ring on fuel fill missing.

[dave4boats]

You could have mechanic hook up a small remote fuel tank to see if boat runs better. I just did this for a friend and boat ran great. So I drained his tank on boat and out of 35 gallons i got about 12 gallons of water. One can of seafoam and 15 gallons of high test boat back to normal. He has had issues for about two years, found o ring on fuel fill missing.

[mmwjr]

Phase separated ethyl gas can not be fixed by additives and hightest. Must be pump out and disposed of. Trying to run on it can damage the engine.