225 Promax - rough idle and no warm start

[I/O to O/B]

Thanks guys. Always great to get good advice from fellow Ally owners.

 

[I/O to O/B]

After reading this again it sure sounds like classic diaphram pump not keeping up? She takes of fine from the get go because at idle it can still fill the vst enough to make a run to wot. Because the motors cold you idle longer before ya take ask for the demand. Then you back off and shut down. because the engine still warm you start up after depleteing the vst on the last run but take off wot sooner than you did from the cold start but the week spring didnt have as much time to fill the vst this time and presures not there for idle then you take off and it just doesnt have the fuel to meet the demand the second time around??

I mean you can also do as Chad said. Before I got the Bruacto ACU and used the TPS Ive checked that thing and it was jumping around on me. Thats when I bought the Brucato acu so I could eliminate the tps as the brucato unit does that for me.

Also fuel issue. I would drain the tank change the filters and plugs replace the diaphram pump. Swab the tank if theres any particals in there also with a rag tie strapped on the end of a coat hanger. Then try her again. That way at least you eliminated fuel as a problem also.

It's the re-start when she's warm that's the problem. When I turn the key, you can hear the starter engage, and there's an instantaneous burp, almost like a short "pop", then there's only the whine of the starter (still engaged?), but not cranking. I back off on the key again. The very next attempt at a start it usually cranks more, but will then do the same thing, just a few seconds later/more. Like I said, it seems to me like its flooded, too much fuel for the start. If it DOES start up, then I have all the same symptoms, rough idle, belching and shaking up to 3000 rpm, then when she's on plane she just rips. If it was bad injectors, I assume she wouldnt run perfect on the top end? I've been running Quickkleen through with every tank of gas...

 

[I/O to O/B]

Not that I am going to run out and buy it, but I assume this is the stator I would need to buy?

http://www.ebay.com/itm/Mercury-Racing-High-Performance-Stator-V-6-Bridgeport-Promax-2-4-2-5-liter-/330909588277?pt=Boat_Parts_Accessories_Gear&hash=item4d0bbf9b35&vxp=mtr

 

[njj502]

I don't think you want that one. You want a 40 amp I believe.

If it's flooding at idle and not up top you need to check that MAP hose. If it's come loose or broke the MAP sensor is essentially telling the ECM you are wide open since there would be no vacuum. That is how the MAP works. At idle you have the most vacuum and the MAP corrects the fuel mapping for low speed/high vacuum. Once you start opeining the throttle vacuum drops and the MAP changes the fuel map. At WOT there is 0 vacuum and I suspect that is why it runs good up top.

 

[whipper]

Like NJJ502 said. It take me 5 times to read somthing and understand it. :big grin Missed the no start thing ya thats differant than pulse pump. What about your air fuel screw?? They have been knows to back out also? They will make starting or idle next to impossaple if not correct. Also as Chad has mentioned the TPS will make life miserable if not working right like your issues. Even a bad ECU has issues like this so ive been told?

Stator, switchbox. I hope you nail it before ya have to go threw everything.

 

[njj502]

A loose air screw would cause a lean condition and VERY high idle.

 

[SLOmofo]

Check the throttle plate to see if it's held open slightly.

 

[whipper]

A loose air screw would cause a lean condition and VERY high idle.

Ya or in. mine needed adjusting to smooth out the idle or it would stall. Lots of fiddle farting around. Link and sink as Gary mentioned also. If you have changed or replaced your ACU/ECU at all some times theres some tunning to be done like these things. Bad gas ect.. its such a broad condition you have. Its like My motors not running right idles rough what could it be:] Lots of differant things.:banghead

 

[bec]

I know on a 280 if it is not dead nuts on adjustments ,butterfly, tpi .they will act like the that.hard start lean sneeze.

 

[I/O to O/B]

So, I checked the MAP hose and it seems fine. In fact I ran the engine with the MAP hose disconnected and the engine ran in almost an identical fashion except it did run slightly worse. All of the exact same symptoms though. Is there anything else I can check myself? There was a post above regarding a screw. Where exactly might that sucker be? Thanks guys.

 

[dragmerc]

i had the same issues on a 260. i tried 3 different 'used' merc puters and all had same symptoms. stupid rich after warm-up. had to hold throttle open to even start it. ran fine on top. put on a brucato box and all problems went away. idled great.

 

[SLOmofo]

What I might do is take a vacuum pump and apply vacuum to the MAP sensor. Play with it, see how it idles. Then release the vacuum as you get on plane then pull a little vacuum, only a couple of inches, again for a SHORT time. You might have to put new plugs in it before doing this.
I tested manifold vacuum on my engine trying to prove someone wrong. At idle there is a little vacuum. On acceleration none. But once the speed meets the throttle opening the vacuum builds again. Not much, but it's there!

 

[I/O to O/B]

slo - so, where do I get a vacuum pump that would do the job? Tried the wet-vac, but attachment was a shade too big. Oh, and why would I have to pull a couple plugs?

 

[SLOmofo]

http://www.bing.com/shopping/search?q=Hand+Held+Vacuum+Pump&FORM=RSLPCA#x0y492

I would aSSume the plugs are fouled.

I have a Vaculla and a snap on.

 

[I/O to O/B]

FIXED!! One WAG of an adjustment of the TPS and it runs like the day she was born. Course, that's after I bought a voltmeter, compression tester and vacuum pump, but who cares. Thanks guys.

 

[njj502]

Sweet!

 

[I/O to O/B]

f&$@! She runs much better on the low end, but she is still rich at idle AND she still will not warm start. She floods. Lt her sit for half an hour and she roars on the first half turn of the key (even at cold she's getting tons of gas. I've got the tps pretty much turned all the way in the one direction (the direction that improved the low end end running) , so I'm at a loss now.....

 

[njj502]

Fuel pump maybe

 

[SLOmofo]

I can only tell about my engine. Frankenstein OMC. The TPS is critical as to where it says closed throttle is....... and where WOT is. The fuel map uses those points and everything in between to supply the correct amount of fuel for the rpm.
It could also be in richening due to a temp detect sensor (air or water) out of calibration.

 

[silverbullet02]

What is your TPS set at now? Have you operated the throttle while watching the TPS voltage to ensure it was operating correctly? I know they're sensitive. Set it and it'll even change sometimes while snugging the screws.