Jump to content

Welcome to TheMalibuCrew!

As a guest, you are welcome to poke around and view the majority of the content that we have to offer, but in order to post, search, contact members, and get full use out of the website you will need to Register for an Account. It's free and it's easy, so don't hesitate to join the TheMalibuCrew Family today!

Sign in to follow this  
chadwick02

Dead spot on throttle? Boat feels like it wants to stall

Recommended Posts

chadwick02

Alright – this problem has been plaguing me since I bought the boat back in 2006. I think I maybe have even asked the same questions a year or two ago, but I have not solved the problem yet. Now its beginning to drive me more and more crazy, and I want to fix it. Here's whats up:

The Problem: While accelerating, the boat seems to "die" or "hesitate" significantly. Sometimes it will back fire a little, sometimes not. It will never completely die or stall out, but it momentarily drops back several hundred RPM's before it "catches" its self and then continues as normal. This problem consistently happens right aroudn 1200 RPM's, every time. The motor is a monsoon (fuel injected). Depending on how the driver accelerates, the characteristics change:

Slow acceleration (surfing): real bad hesitation, to the point where sometimes it screws up my surf launch. Were surfing more and more, and its really beginning to bug me now.

Medium acceleration (skiing and boarding): when the boat hits 1200 RPM +/- the RPM's drop by only maybe a few hundred for a second, then the boat resumes acceleration as normal.

Hard acceleration (dropping the hammer): Hardly any hesitation at all. Barely noticeable.

It almost seems like a dead spot in the throttle or something like that? I have replaced the throttle position sensor, and that did not fix the problem. The boat sees regular maintenance and tune ups. It has a new high pressure fuel pump and I replaced the fuel filter 20 hours ago. The boat runs like a top other than the hesitation issue. I just don't understand why it drops RPM's so quickly under slow acceleration. It is a very uniform and consistant problem. It always does the same thing at the same RPM with the same type of acceleration. Is there a diagnostic tool I can hook up to the computer to see what it is doing when the problem happens? It seems like maybe a sensor or computer issue to me? But I've really got no idea where to go on this issue now.

Any insight or ideas as to what to try?

Thanks,

Chad

Edited by chadwick02

Share this post


Link to post
UWSkier

your dealer should be able to tell you if your ECM is throwing any codes. Do you have a fuel pressure gauge? It would be interesting to see what your fuel rail pressure looks like during one of these incidents.

Share this post


Link to post
SmoothWaterMan

Personally I'd take a look in the ignition area, due to the backfire. Check timing, cap/rotor/plugs/wires/ bad connections - anything to interrupt spark.

Peter

Share this post


Link to post
edwin

Does this happen only when PP is engaged?

Share this post


Link to post
chadwick02
your dealer should be able to tell you if your ECM is throwing any codes. Do you have a fuel pressure gauge? It would be interesting to see what your fuel rail pressure looks like during one of these incidents.

I do have a fuel pressure gauge - I never thought of using that. Ill grab it while im at home and bring it up to the lake this evening and see what it says.

The dealer is 2 hours away, and I'm sure booked for weeks. If it comes down to that, Id rather just live with the issue and take it to them in the fall.

We DO have an awesome old school local chevy garage (small town GM dealer). They are allways willing to take on a good challenge, and have helped me with some pretty technical engine issues on this boat in the past. I wonder if it is anything they could trouble shoot a little? Are the computer hookups on the monsson the same as they would be on say a late 90's chevy with the same engine? Would a engine mechanic be able to take a stab at this? If I brought the boat and the fake a lake to them for a day, I know they'd be willing to futz with it. I just dont know if it is simmilar enough to what they deal with every day to make it worth while?

Personally I'd take a look in the ignition area, due to the backfire. Check timing, cap/rotor/plugs/wires/ bad connections - anything to interrupt spark.

Peter

Thanks Peter! I replaced the cap, rotor and plugs mid season last year with no improvement. I did not replace the wires - they look to be in good shape and seem pretty expensive. I have not checked the timing, i could do that. I pretty much wrote off the timing as being an issue since the issue is limited to such a small RPM range.

Does this happen only when PP is engaged?

It has nothing to do with PP. I only installed PP a few days ago, this has been going on for quite a while. It exibits the same issues when it is engaged or not.

Edited by chadwick02

Share this post


Link to post
SmoothWaterMan

I'm tied up next week, but if you want to try and look at it Thursday/Friday of this week, or the week after next, shoot me an email and we'll take a look.

Peter

Share this post


Link to post
chadwick02
I'm tied up next week, but if you want to try and look at it Thursday/Friday of this week, or the week after next, shoot me an email and we'll take a look.

Peter

Thanks for the offer peter! You are pretty far away, so at this point I think I'm gonna try to fix this on my own. I'm sure it would be much simpler and faster to take it to you, but the gas to pull the boat 300+ miles round trip is gonna kill me...

Share this post


Link to post
chadwick02

would the octane of my fuel have anything to do with it? I've run 91 or 92 since the day I bought it. I know there are plenty of you that burn 87 or 89 with no problems. Would that have ANYTHING to do with the problem?

Share this post


Link to post
99response

I second Peter's timing idea.

Share this post


Link to post
SmoothWaterMan
I'm tied up next week, but if you want to try and look at it Thursday/Friday of this week, or the week after next, shoot me an email and we'll take a look.

Peter

Thanks for the offer peter! You are pretty far away, so at this point I think I'm gonna try to fix this on my own. I'm sure it would be much simpler and faster to take it to you, but the gas to pull the boat 300+ miles round trip is gonna kill me...

It's 140 miles each way. Don't be so negative, keep the economy going! hehehe, No worries, let me know if I can help.

Peter :)

Share this post


Link to post
VinRLX
I second Peter's timing idea.

Timing with you. Always timing. Why don't you go over there and check it for him???

Share this post


Link to post
chadwick02
It's 140 miles each way. Don't be so negative, keep the economy going! hehehe, No worries, let me know if I can help.

Peter :)

I second Peter's timing idea.

Timing with you. Always timing. Why don't you go over there and check it for him???

Plus1.gifPlus1.gif

Share this post


Link to post
99response
I second Peter's timing idea.

Timing with you. Always timing. Why don't you go over there and check it for him???

Well I could suggest he makes sure his prop nut is tight and sent him on a wild shaft alignment chase....

I'm pretty sure Peter is closer than me anyway, plus I'm on a pretty tight sechedule here, I have class EVERY day until 11:30 AM, except for Friday, Saturday, Sunday when I have no class at all.

-Chris

Share this post


Link to post
chadwick02
I second Peter's timing idea.

Timing with you. Always timing. Why don't you go over there and check it for him???

Well I could suggest he makes sure his prop nut is tight and sent him on a wild shaft alignment chase....

I'm pretty sure Peter is closer than me anyway, plus I'm on a pretty tight sechedule here, I have class EVERY day until 11:30 AM, except for Friday, Saturday, Sunday when I have no class at all.

-Chris

Peter's a pretty classy guy all the time. If you've got no class on the weekends, then I suppose I can only see you during the week Biggrin.gif

Share this post


Link to post
VinRLX

ROFL.gif

VERY good. And how many days must I endure getting the shaft on the alignment thing.

Share this post


Link to post
99response

Until you say something else I can make fun of you for....shouldn't take too long.

punk.

Share this post


Link to post
chadwick02

Thanks everyone for your ideas. Sorry Edwin, I did not mean to shut you down quite like I did – my apologies if what I was trying to say came across as being rude. I know you were just trying to help and I had no intention of putting down your idea.

Late last week peter sent me an Idle Air Control unit and a throttle position sensor. The boat was having some idling while cold issues too, which I probably should have mentioned earlier. Peter diagnosed that as the IAC over the phone, and sure enough, a new IAC took care of the boat stalling while idling cold when it was put in gear. So we solved that problem, but we still have not solved the main issue with the engine trying to stall its self while beginning to accelerate.

I did not try out the throttle position sensor he sent me – I was able to put a volt meter on my existing one and that seems to be acting fine, so I don’t think it is that. I put a fuel pressure meter on and it does not seem to blip when the engine does, so I don’t think it’s a fuel problem.

So what else can I check??

I’ve got a timing light, but I have not checked the timing yet. Someone said you have to put the engine into “timing mode” and I don’t know how to do that on this engine.

Also, something I should mention: The boat did sit out side, mostly un-covered for over a year before I bought it. It did have some water sitting in the bilge when I found it. Components susceptible to moisture have had some issues (starter, alternator, steering cable..etc). But those were all replaced 2 years ago now and everything seems to be running great, except for this stinkin hesitation. The motor has 160 hours on it now.

It has been almost 80 hours since I changed the cap and rotor. Replacing them last year never solved this problem, but maybe I’ll get a new set now, and while I’m at it new plugs and wires too? Does that sound reasonable? None of those are terribly expensive. What about a MAP sensor?? One of the guys at work suggested that.

Thanks,

Chad

Share this post


Link to post
99response

Motor has to be put into timing mode to check the timing. There is an easy way to do it if I remember correctly, but I've always just used the service computer.

I would say doing plugs and plug wires wouldn't be a bad idea with the age of the boat.

In terms of sitting outside, that SS VLX I just sold sat outside w/no cover its ENTIRE life, ran like a clock.

-Chris

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...