Suzuki DT150 max rev 4300RPM

[Speargun]

I've got a pair of 1998 Suzuki DT150's with less than 100 hours that run fine until they get to 4300 rpm. They then fall flat on their face. The only way to get them up to speed is to ease open the throttles and then only to a certian point. If I push the throttles wide open, the engines bog down. The only difference is on free revving; then they will rev up without a problem.<br /><br />If I restrict the airflow at the intake while underway at 4300rpm, I can get the engines to increase rpm which tells me that they aren't getting enough fuel. Both engines were doing the same thing, so I took them to a Suzuki dealer to check out. After more than 6 months and 20 plus hours labor, the diagnosis is that the computers needed to be replaced due to a possible lightning strike.<br />Has anyone here ever seen this problem? Does this diagnosis sound correct? I would hate to spend over $2800.00 on comuters and that not be the problem.<br />Thanks in advance.<br /><br />P.S. All electrical components checked out OK (TPS etc..) and the engines had the same problem on a dyno as in the water.

 

[jim dozier]

Re: Suzuki DT150 max rev 4300RPM

You have diagnosed the problem correctly, now the question is what is the fix. This is an EFI engine so its a bit more complex. The Suzuki dealer should be able to tap into the computer for the error codes to nail it down.<br /><br />The engine will rev in neutral because it has no load and no back pressure so that doesn't tell you anything.<br /><br />Don't run these engines like this (lean) or you may cause cylinder damange. The good news is I think your oil injection is separate from the fuel system (at least it was on the carb versions) so you are getting some lubrication. Hopefully someone here has a more definitive fix. Are the engines still under warranty? Did they always do this or did this happen after you got them. It seems odd that a lightning strike would affect both engines identically but I suppose its possible.

 

[craw]

Re: Suzuki DT150 max rev 4300RPM

This sounds like typical bullsh*t from someone who doesn't really know what the problem is so they try a few different things (at your expense). <br /><br />I would try the simple things first. <br /><br />I have the same motor and have no drama, but it sounds like it is starving for fuel at a particular rev range. For both motors to do it simultaneously, I would say it is a physical problem with an air leak in the fuel line, blocked fuel filter, or something similar. <br /><br />I would go over the entire fuel system and make sure that it is OK. $2800 buys a lot of fuel lines and filters!<br /><br />The service manual has a good section on trobleshooting problems like this. It would be worth getting and having a read through.<br /><br />craw

 

[micel]

Re: Suzuki DT150 max rev 4300RPM

It has to be something that would affect both engines.Has this always happened or just begun?

 

[JUSTINTIME]

Re: Suzuki DT150 max rev 4300RPM

sounds like the iac valve needs adjustment

 

[lakensea]

Re: Suzuki DT150 max rev 4300RPM

sounds like the iac valve needs adjustment

No IAC valve on a 2-stroke.

 

[lakensea]

Re: Suzuki DT150 max rev 4300RPM

Make sure the engines were run on a remote tank, and still had the problem. The only ways lightning could cause a problem would be if the boat was actually hit, or if you had a battery charger hooked up and lighting struck near by. Also, if you reversed the battery cables on both engines and tried to start them. Also make sure you are using a Suzuki Super Service dealer who has been a dealer long enough to have experience with the 2-stroke models.

 

[spoolinawdtsi]

Re: Suzuki DT150 max rev 4300RPM

I have a 88 dt150 an has the same damn problem, free rev out of water but put it in an revs slow! It's almost impossible to put it in gear cause it just bogs an dies. So many times sitting on the boat ramp an not launching cause of this! I've done cleaned the carbs!

 

[lnghrn]

Re: Suzuki DT150 max rev 4300RPM

I have a similar problem with my 2003 Suzuki DT150. I've had the motor for 5 years and noticed this past year that I wasn't getting up to 5200-5400 rpms like I used to; now I was getting 4800. It really started giving me problems when a trip or two ago it felt like the prop was slipping. The motor never lost rpms, but the propulsion stopped. I cleaned the fuel filter to see if this would fix the problem. I didn't experience the same prop-slip problem on this last trip, but on the way back to the ramp, I couldn't get the rpms above 4400 and the motor seemed bogged down at those revs. I checked the plugs and they all look fine (replaced 2 months ago). I'm going to replace the oil filter, fuel line, and impeller; as all those services are due. I added a hydro foil to the motor 3 or 4 years ago and haven't done anything else to the motor other than the scheduled maintenance and an occasional fuel injector cleaning additive. If anyone has a diagnosis or solution to this problem a reply would be greatly appreciated.

 

[Jhuny]

Re: Suzuki DT150 max rev 4300RPM

I have a 86 model with the same issue. How did y'all resolve the issue?