PDA

View Full Version : I need a tune up??



TRU-JACK
08-16-2001, 01:13 PM
When i'm running at 75% to WOT, i get a small miss or cough in the engine when i use the power trim. Am i getting interference from the power trim moter that is affecting my engine. Any suggestions... The engine is the 4.3LX 4bbl mercruiser on an 89 sweet 16. thanks for any tip or suggestions. :confused:

Formula Jr
08-16-2001, 02:50 PM
Thats a new one..... see the trim pump motor would have to have a consistent arc or short of some kind cause it doesn't know what throttle you are at, so your miss would be thru out the engine range. Something like this needs to have the systems isolated and tested. I'd be looking at my trim wiring first since the miss ONLY happens while using the trim. And only at 3/4 throttle. Then look for some sort of short in your throttle handle - which is where your trim and ingear/start /safety switches are and see if there's any thing metal in there that could contact you trim switch wires with the safety switch. It has to have something to do with the throttle position while the trim leads are hot.

TRU-JACK
08-16-2001, 03:25 PM
Thanks Formula Jr. I will check out the throttle etc... I think i'll also change the plugs, wires etc... any suggestions as to which brand i should use. Is there a difference between the standard mercruiser and some after market performance brand? If so, what brands do you reccommend.
thanks ;)

Formula Jr
08-16-2001, 03:44 PM
There is one wire set I would never use again. Its called magstar stainless. They must have put out a bad bunch of them as the rubber insulation totally failed and cracked on the sets I have bought. As to plugs and such, I don't see much difference in the brands as long as they are marine and you use the correct heat range and gap, but some people swear on certain brands. When you are changing the plugs though, and this happens alot, use a quality driver and try as best you can to keep inline with the plug as you tighten them down. Any side force can crack the insulator slightly and set you up for a failure while you're on the water.

TRU-JACK
08-16-2001, 03:56 PM
Thanks again, Formula Jr. If the rain stops I'll get at it tonight and enjoy for the weekend. Any advice as to what engine oil i should use. I may as well change it when i'm doing the plugs, wires, etc...

thanks

Formula Jr
08-16-2001, 04:24 PM
Well, since you're in Canada, I'd imagine the water temp isn't above 70 degrees, so I'd use a straight 30 weight, I usually buy the auto stuff that is turbine rated. Like anything else, there's differences of opinion on what kind of oil to use.

Rootsy
08-16-2001, 05:45 PM
if you want a tad more performance you can go for an extended electrode plug... which means the inner electrode and insulator is projected past the end of the threads which puts the spark further into the cylinder. Champion makes a standard, extended and extra extended... i believe the AC Delco MR43TS is the extended whereas the MR43T is the standard. Platinum plugs just offer a harder electrode which won't round off as quickly. I just use regular extended electrode AC Delco plugs since i change them every spring...