Hey guys,
Just went out for the maiden voyage of the 27 fountain today and have a couple of issues I could use some advice on.

1997 502MPI rebuilt stock with the exception of CMI headers.
Mefi1 system
All new fuel, timing checked and double checked, fuel system purged and primed.
Code scan showed a MAP sensor fault that was cleared and did not show back up while running on the hose.

Issues:
Idle is very pulsating and seems low. When putting in gear or when backing off the throttle, the motor will die, but will start right back up no issues at all. have to keep it about 1200 to keep it from dying. Doesn't die everytime, but frequently. Docking is difficult this way!!
Issue two: What is a safe oil temp? running 210 at putting around speed, 250 at gentle cruise, but when I ran it up to about 4000 for only a minute, temp was reading close to 310. Is that ok? I fully cleaned the oil cooler before putting back together, and I have a solid 40-60psi oil pressure while running. My water temp is not even getting to 140 on my guage.
There is alot I don't know about this boat, as I bought it in non running condition. I don't know if some of the senders or sensors are bad.

Any help is Greatly Appreciated as always!!

310 is too too hot,you want around 190*..you may have the wrong temp sender for the gauge,always make sure the mfr of the gauge matches the sender..i hope your running a oil cooler? are the lines going in the rite direction? you want the oil to flow the opposite direction as the water flow (X) as for it idleing afu,,how did you check the timing? did you ground the aldl connector? that could be off of you may have a vacume leak..

In response to you idle...have you changed your fuel filter?

I will have to double check oil flow direction, yes it has the standard 2-1/2" or so by 10" or so oil cooler. The guages are factory fountain, and the sender "looks" to be the original, but don't know for sure. All new filters for fuel, oil, etc....
Can a bad IAC or MAP sensor cause the surging idle and dying?
Does the oil flow out of the engine through the center hole or the side hole on the filter mount, I have a remote filter on the transom. Currently plumbed out of center hole, into "top downriver side" of oil cooler, out of bottom of oil cooler "upriver side" into filter and back to side of engine oil filter mount. This appears to be the way it was plumbed prior to me getting it.................but as we all know that means nothing.

The IAC can cause the surging and poor idle and I do not believe the IAC throws a code.
Your oil temp is WAY too hot.

FROM the remote filter, the oil returns to the motor thru the CENTER port. FROM THE MOTOR the oil leaves the motor thru the outside port...

so its outside to outside , thru the filter, out the filter thru the center, to the cooler, out of the cooler back to the motor to the center.

good oil temp is 200 min to 230 max. anything colder is wrong, anything hotter starts to become an issue to 300 where it starts getting critical.

and your idle issue on the face of it sound like the iac but then again, any pad connection on any sensor will do this as well as having the water temp too cold...

but the iac sounds like the culprit... take it apart, clean it and execise it... make sure it moves and try again.

and obviously vacuum leaks and all sorts of sht will screw you up.

but the bottom line is if you find your oil plumbing is correct, and the oil temp is shown correct, then do not even start that motor again until you discover that cause because having the temp spike with no real load like that is a certain indication of something catastrophically wrong inside. right now you might be able to save it but if you spin the bearing or something actually breaks then you are screwed.

Any chance you changed the dipstick or dipstick tube? Too much oil in pan will make high temps. Usually the pressure will get flaky also. Where exactly is the oil temp sender?

Do you have an IR temp gun you can poke around with?

Ok so I have the oil lines going in the wrong direction. And I put 7qts in the. Engine with everything bone dry. Should I add any for remote oil cooler. I took it to a good merc mechanic friend before the lake test and he said it was 2 qts low an topped it off ( so maybe my dipstick is in a little off and reading low?). So maybe I have been running 2 qts high.
I will change oil lines and remove some oil.... Run again and update.

When trying to find a problem its not a good thing to change two or more items at a time and try and find the problem. It sounds like you have the oil flow direction wrong and you would not be cooling the oil or filtering it properly with that hookup becuase the oil is not going thru the cooler or filter at pressure but bypassing back to pan. That engine has a 6 qt in the pan and 1 qt in the filter, cooler and lines capacity so 7 quarts sounds right. don't reduce the oil to 5 quarts until you get the oil plumbing direction correct and the oil temp in nthe 190-230 degree range unless you see obvious signs of oil foaming on the dipstick. You can always readjust the oil level slightly after verifying dipstick height, system capacity, etc. , get the oil plumbing direction and temps right first.

Yes a bad MAP or IAC acting up can have a big effect on idle quality as well as a manifold vacuum leak. Map bad should show up as a trouble code but not generally the IAC. You can use the squirt bottle full of water and spray the manifold while idling to find a manifold vacuum leak.

Best Regards,
Ray @ Raylar

Thanks for the advise Ray, I had 7 qts in and then the merc mechanic put 2 more in for a total of 9. I probably should suck two back out and remark the dipstick with a known 7 qts in right?