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Throttle won't let me hit an exact speed - moves from 28mph to 31mph almost immediately.


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Any reason why my throttle wouldn't be consistent across all rpm. It seems to jump a bit in the tac between these speeds. The boat is a 1999 malibu response.

Any idea what that would happen, thottle cable, or something else?

Appreciate any insight into what to check...

Thanks again,

jeff.

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What engine and prop?

It sounds like a little surging at that particular rpm. I can't say that we have the same problem with our '98 but 28-31 isnt a speed that we regularly run.

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It's EFI and I'll have to dig up the specs on the prop. Do you think this is an EFI mapping issue? It doesn't have perfect pass installed..

Thanks again for your help, look forward to your responses,

Jeff.

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I believe there was an issue with the fuel lines in this era monsoon. Check the cross over lines between the two fuel rails and see if the line is solid metal or has a piece of rubber hose in the line.

I may be wrong on the years this effected, but read this thread for more info http://www.themalibucrew.com/forums/index.php?/topic/24722-suspected-air-in-fuel-system/page__p__362883__hl__+fuel%20+hammer%20+cross%20+over__fromsearch__1#entry362883

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If the cap and rotor does not affect it, then the cross over lines as 99response mentioned is the next step. It's due to a fuel hammer issue on bank fired engines.

Peter

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The diagnostic technique is to hook up a fuel pressure gauge to the engine (fuel rail shrader valve) and go run the boat. If it's a fuel hammer issue the rubber line on the fuel pressure tester will absorb the hammer and the problem will disappear. Remove the fuel pressure tester and the problem will come back.

Naturally make sure to bleed the pressure and only install or remove the pressure tester when the engine is off.

Peter

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"Fuel Hammer" There is really no way an average boat owner or even a good Malibu boat owner would have ever discovered "Fuel Hammer issues" without hanging around on this forum. Literally one could suffer for years and never ever guess this one. I am amazed. :cheers:

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Any reason why my throttle wouldn't be consistent across all rpm. It seems to jump a bit in the tac between these speeds. The boat is a 1999 malibu response.

Is this a problem that is just now surfacing after 12-13 years?

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It wouldn't surprise me flapjack. We fixed a '99 Response with this problem a few years ago, and either no one skied there until now or it developed over time. Wouldn't surprise me if the injectors get worn or gummy and slam harder than when new. Or, the short length of rubber cross over line gets old and brittle and can no longer flex enough to absorb the hammer impacts, which makes more sense now that I say it.

Peter

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I believe Indmar knew of the fuel hammer issue back in 1999 when they changed the design to the rubber cross over lines.

I struggled with the issue of the engine not wanting to run between 3500-4000rpm for over five years and tried everything under the sun to fix the issue, and I was convinced that the problem must have been in the ECM; but since the issue didn't affect us at the speeds we ride I just lived with it and banged my head against the wall every now and then trying to find the fix. When I tested the fuel pressure the problem indeed did go away but at the time 5 years ago I didn't connect the dots and sure in the heck didn't even consider fuel hammer, I thought the problem was just screwing with me like it was intermittent.

However today I am happy to report that because of MalibuCrew and people like you who take the time to help each other; the problem has been fixed and the solution was as simply as replacing the steel crossover fuel lines with rubber lines I had made at a local hose shop for $70.

So for anybody who has a monsoon that with steel crossover lines I highly recommend you replace them with either the factory replacements or just have them made and save a few $$. Oh and if you have them made just use regular fuel line, it doesn’t have to be high pressure line like 3000psi, in fact the high pressure lines might not solve the problem due to the fact that they are to rigid and do not flex enough to absorb the shock wave created in the fuel system. Another poster used high-pressure lines and although it did help his problem it didn’t solve it completely. I think the lines I used were rated at 300psi but even that is way more than the 30-50psi of the system.

Thanks

Selle

Key words/phrase: "Dead Spot in Throttle" "monsoon won't run at certain RPM range but runs fine outside that range" "Engine acts as if it's starved for fuel, hanging up at RPM and then as you advance the throttle more and more it suddenly jumps past that rpm range and runs fine"

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I believe Indmar knew of the fuel hammer issue back in 1999 when they changed the design to the rubber cross over lines.

So for anybody who has a monsoon that with steel crossover lines I highly recommend you replace them with either the factory replacements

You are correct in these statements. Indmar did learn about the issue and changed over to rubber cross over lines for this exact issue. The customers that are experiencing the hammer issue now after 15 or so years are already using the rubber cross over lines. My belief is that it's an injector wear or hose deterioration issue, perhaps along with a slightly more aggressive timing on some engines due to the hand that timed it. This is all theory, but in the end the same solution applies: add a larger dampener and the hammer goes away. Our fix for those with rubber cross over lines have been to replace them with criss-cross lines, for a longer length.

Peter.

Edited by SmoothWaterMan
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  • 4 weeks later...

The diagnostic technique is to hook up a fuel pressure gauge to the engine (fuel rail shrader valve) and go run the boat. If it's a fuel hammer issue the rubber line on the fuel pressure tester will absorb the hammer and the problem will disappear. Remove the fuel pressure tester and the problem will come back.

Naturally make sure to bleed the pressure and only install or remove the pressure tester when the engine is off.

Peter

I ordered a "X Over kit" from skidim, but only got one xover with the rubber hose. I think i need another and i think they shorted me. Can anyone confirm?

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