engine missfire / popping at my wits end

[laurie88]

excalibur 330 hp 2007 only 400 hrs

started by no acceleration at hole shot and then picked up, also seem to have idle surge.lost a bit of power on the turn
Now when i accelerate and get to 1700rpm every time the engine will not go any faster and starts misfire/ popping sound

changed fuel filters, pumps, air filter clean, plugs, ht leads, coil lead, ran on new seperate tank of gas, put in fuel additive. new distr cap, distr rotor, ht leads, coil lead

no engine warn light, no overheat, starts first time as usual and idles as normal , no cut out, good compression, good fuel pressure

anybody any ideas, could it be throttle sensor???.....coil????

trying to get diagnostic tools,

[teamseal]

Did you put a fuel pressure gauge on it?

[laurie88]

missfie

yes fuel press good 65 psi

[ClemsonDave]

After you run it, do all the spark plugs look the same? Are the all firing? Try going WOT, then shut if off immediately (not run at lower throttle), take a look at plugs.

Did you replace the ignition coil?

[laurie88]

misfire

all plugs look the same did not change coil

been told by dealer (whom i described symptons to) that it could be the oil pressure sensor, which if faulty can limit rpm and pcm had some probs with them and changed them out??

could it be p pass problem??

cheers

[snowboardcorey]

A bad oil pressure switch could/would put your boat in limp mode, not sure that it would make your boat surge at idle though, that sounds more like a throttle position sensor.

[NautiDave07]

My ZR6 did something very similar and Dealer swore it would be throttle position sensor. They were wrong and turned out to be crank sensor

[ffmedic74]

Did you check voltage. I had the same issue...turned out that the injectors were not getting enough voltage due to a bad battery.

[thekneeboardking]

I actually have the same problem where is the oil pressure sensor? So I can swap it, I have changed many parts and still no luck.


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[Joshua J Rowe]

A plugged up exhaust can cause symptoms like that. Not sure what the exhaust system is like on your boat. My exhaust fills up with water. I can imagine if some debris got in there it could plug up and essentially hydrolock itself. Probably a far shot, but something to think about.

[homer12]

From an old fuel injected Jeep I used to have, this sounds like the same problem. Would totally bog down under throttle. I would start by checking throttle position sensor. You should be able to check volts on that and somewhere you should be able to get what volts it should read at idle and under more power. PCM may be able to provide that. They should also tell you what you should expect to read on the oil pressure sensor for testing it as well.

[ally505]

You've pretty much renewed the whole HT ignition. I'd be checking the alternator output. You can get all kinds of gremlins if the voltage is low. Check for corossiom, bad earths etc too.

[thekneeboardking]

I have finally found the fault, the fuel pressure was down to 40psi and after swapping for a new one it is now between 55-60 and all the problems have gone.


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[93Euro]

I have finally found the fault, the fuel pressure was down to 40psi and after swapping for a new one it is now between 55-60 and all the problems have gone.


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I think this is one of my issues also I finally put a fuel pressure gauge on mine and it was at like 46