1998 SeaRay 230 BR 5.0L Alpha I misfirse, surging issue??

Well let me say I new to this site and I am requesting a little advice on where to locate the problem that I have with the boat.

The boat is a 1998 Sea Ray 230 BR with a Merc 5.0L Alpha I driveline. The boat has just over 800hrs on it. I have had the boat since new with no major problems. This problem I can not narrow down to the exact cause. We usually cruise it around 2700-3000 rpm range. In this cruise rpm range I have felt the boat feel like it has a loss of power (fuel, spark, bog). It is like a 1 second pause or very short surge of power. This loss of power feeling can last a short time but in many repeat times, such as a duration of very short pauses over a few minutes. Any rpm above 3000rpm it has never performed this loss of power. The rpm gauge fluctuates all over the dial in the gauge range when operating at 2700-3000rpm, above that it starts to read acurately. When the gauge does not read acurately is when the problem happens the most but has happened when the gauge is reading correctly. Ive heard a pop sound when the engine did this surge of power. I am assuming it is a backfire of some issue either related to fuel or the floating tachometer.

I have replaced the Distributor Cap, Rotor, Pick-up, Module, Coil, Wires, Plugs, Fuel Filter. I still have a wandering tachometer and surging issue around 3000rpm. Also I now have a low idle stall when docking, it mainly stalls when shifting from Neutral to Forward or Reverse. I need to resolve the idle stall and 3000rpm surge/floating tach. Can you guys help me out on the issues?

Re: 1998 SeaRay 230 BR 5.0L Alpha I misfirse, surging issue??

Ayuh,... Welcome Aboard,.... Was there any water, 'n junk in the old fuel filter,..??

This is a carbed motor, Right,..??

I'm guessin', if you haven't changed the lower shift cable yet,...
That's yer stallin' when shiftin' problem...

Maybe you could disconnect the tach wire from the coil, 'n try it,...
The ignition, I guess could possibly be screwin' with the tach,...
But usually it's the tach that's the problem...

If it's Not ignition/ tach problem,... I'd look to the Carb,... sounds like she's goin' Lean...

Re: 1998 SeaRay 230 BR 5.0L Alpha I misfirse, surging issue??

Also Check wiring, grounds, just all electrical connections. Make sure they are clean and tight.

Re: 1998 SeaRay 230 BR 5.0L Alpha I misfirse, surging issue??

It is a EFI TBI motor. I did not notice any water in the fuel filter. I haven't changed the shifter cable but I am not sure that is causing the issue since the RPMs drop down and it stalls. I think its the idle setting or something along the lines of a normal operating temp engine idle stall. I read stuff about fuel pump failure causing lean conditions while running. Is there a way to test the RPM signal wire to a new tach to verify the current tach is bad or if it comes from the engine signal wandering?

Re: 1998 SeaRay 230 BR 5.0L Alpha I misfirse, surging issue??

BUMP....

I know this site can provide me some information on my issue. Help me figure this out...

Re: 1998 SeaRay 230 BR 5.0L Alpha I misfirse, surging issue??

Sounds like you need to hook up a diagnostic computer and have a read of the fault codes. The mid range missing could be that the throttle body needs a clean, or a knock sensor on the way out, or crappy fuel. The idle problem could be a leaky/faulty IAC (idle air control), but you'll definitely need a scan tool/computer to find out...

Re: 1998 SeaRay 230 BR 5.0L Alpha I misfirse, surging issue??

Where could I get a scan tool for the boats ECM or are these dealer only units?

Re: 1998 SeaRay 230 BR 5.0L Alpha I misfirse, surging issue??

http://www.rinda.com/marine/mtspec.htm#techmate

Re: 1998 SeaRay 230 BR 5.0L Alpha I misfirse, surging issue??

Thanks for the link but thats expensive for my troubleshooting. I may have to go see the dealer for a scan. I was debating on replacing the IAC valve just to see if it changes anything due to the year of the boat. Would the TPS sensor have any effect on a varing RPM gauge? Also where do I trace the ground connections on the motor?

Re: 1998 SeaRay 230 BR 5.0L Alpha I misfirse, surging issue??

OK I have done some research and the low idle stall could be a result of the "shift interrupter switch" or "lower shift cable". Is there anyway to test either of these items easily without taking to a dealer?

As far as the wandering Tach gauge, I still need to trace down all the grounds on the engine and clean them then reconnect. I hope the gauge wandering/surge misfire relates to a bad ground but I can not tell yet. I need to do some digging on the wiring before I take it to a dealer. Does anybody else have any ideas on a possible cause?

Thanks!!

Re: 1998 SeaRay 230 BR 5.0L Alpha I misfirse, surging issue??

Litigator said:

OK I have done some research and the low idle stall could be a result of the "shift interrupter switch" or "lower shift cable". Is there anyway to test either of these items easily without taking to a dealer?

As far as the wandering Tach gauge, I still need to trace down all the grounds on the engine and clean them then reconnect. I hope the gauge wandering/surge misfire relates to a bad ground but I can not tell yet. I need to do some digging on the wiring before I take it to a dealer. Does anybody else have any ideas on a possible cause?

Thanks!!

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Did ever figure out what the cause of your surging and tach issues were. I am having the exact same problem on one of my 350 mag mpi engines on my sea ray 310 sundancer.
Any help would be greatly appriciated.
Thanks,
Josh

I know this is an old thread, but I am going to add my information. I fought this problem for a couple of years. After the complete tune-up (plugs, wires, rotor, dist cap) the symptoms changed slightly. Instead of having the tach jumping and boat running rough around the 2600-3000 range, it would happen above 3200 rpm. I stumbled across a youtube video where they replaced the shift interrupter switch for their jumping tach problem. I replaced the switch and PROBLEM GONE.. The old switch ohms good, but I am guessing with engine vibration at certain rpm's the switches internal contact was flakey. I was told by many that this was not ever going to solve my problem. I guess they were wrong. I have a 1998 Searay 5.0l efi. Hopes this helps others..

I know this is an old thread,

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Ayuh,.... That it is,....