29scarab

I did a search and found the thread. Man, thats got some interesting info on it. I have adjusted bot the throttle blades without the scan tool. I can almost guarantee I have the TPS out of whck right now.

I gotta get a scan tool and start all over with again.

Thanks for the help!!

John B

Try opening the primary throttle plate. Mercury had a similar problem on the first 525 EFI's. After I hit the dock a few times due to stalling, and many calls, a factor serviceman screwed the throttle stop in to open the blade, AND THAT FIXED IT. Shorty after the adjustment, the factory changed the specs on the minimum opening setting. Seems, originally, the IAC was too far open under no load idle, and when it was called on to open when put in gear, it couldn't open far enough.

Hope this may help. It took me 3 months to get mine fixed!

29scarab

Thanks John B. I just got the new IAC motor in yesterday. I will be tinkering with it this weekend.

Thanks again for all the input on this

29scarab

Tried the new IAC and did not have any luck. You stick it in gear and it dies.

Is there a way to hook a meter up in line to see what the TPS voltage is if you don't have a merc scanner? I know I adjusted it and shouldn't have.

Thanks,
shawn

John B

29 did you try my suggestion? I put on a new IAC and it did nothing either....

zt260

The IAC will not help if it isn't programmed properly. If you put it in gear on the trailer does it stall? My guess is no. If so you IAC is not programmed properly.

superwrench0166

Possibly the IAC is in the extreme open position allready when running. You may need to drill a slightly larger hole in the Throttle Blades till the IAC can start closing off airflow to control Idle RPM.

zt260

If you use the idle screw to open the throttle plates a little the IAC should close somewhat if it was fully open. Turn the idle screw in until the rpm rises then back up a bit. Then try it again. A properly working IAC is awesome for shifting. It made a world of difference on my whipple.

John B

29 scarab, What did you find out about your problem? We all may be better able to help if we can get some feedback!
JB

29scarab

Latest update,

I went ahead and replaced the IAC motor and the TPS. I have not had a chance to check and see if the TPS fixed it, but for some reason I have my doubts. I posted replacing the TPS on another thread and got some input on some checks.

I got some good input, but I really am hoping someone can tell me how I can check it when the engine is runnning without the scan tool hooked up to it. I had some real small gauge wires pushed into the plug of the terminals with the TPS plugged in so I could get some volt readings. I'm just not sure where to take the vooltage readings when its running to let me know its putting out the proper signal to the ECM.

I did however perform some continuity checks to make sure there were no wires grounded coming out of the TPS going to the ECM. I also pulled the SELOC marine manual out to perform the steps on checking the TPS. After performing the steps, it pointed to the ECM NOT seeing the signal from the TPS. But, I did find someone that had access to a scan tool , and I need to contact him again and set something up to see if the scan tool is reading the TPS at the ECM.

I'm still hoping someone out there can let me know if there is a way to check the TPS with the engine running without a scan tool and what wires to hook up to with a volt meter???

Thanks again for the help on this!!