EFI Woes

[MERC EFI]

Have a 1997 Merc EFI 175. Problem is sometimes it will plane up and run sometimes it won't(under load). Encounters a serious surge problem. The computer and sensors have been checked. They are OK. If I take the motor out of gear,rev it up to a little over 1500 rpm let it calm down it will plane and reach WOT with no problem so lon as I don't let out of the throttle appears to surge around 3500-4000 RPM push the throttle back up and it goes away. Have checked everything I know by the book(I'm no dummy)Last resort is to clean the injectors and if this doesn't work I'm lost Already drained the fuel and added 2+2 no help Checked fuel Pump out put and it's good. Any help anyone can give would be greatly appreciated. Marine dealer can't figure this one out either. null

 

[clanton]

Re: EFI Woes

Try www.screamandfly.com , the fuel injection guys are there.

 

[Pursuit2150]

Re: EFI Woes

Since you already went to the mech. and everything "CHECKS OUT" I offer the following, Chech the fuel lines for obstructions, pull them off and blow them out, also check the primer bulb.. "Never rev. the engine above 1500rpm, out of gear!

 

[petryshyn]

Re: EFI Woes

Never worked on your engine, but if it was mine, I'd check the throttle position sensor "signal" while the surge is occuring. <br />Tee in, and if you see signal fluctuations, change the TPS.(use a digital meter, not analog)<br />I've replaced several TPS's on other applications that appeared good on the meter test, but failed a screen capture test. Even if the ECM has diagnostic capabilities, the intermitent signal drop out I'm refering to, won't be detected.<br />>If this is a dead-end, tee in and do a fuel pressure test while surge is occuring.<br />>And ofcourse there is always the chance of intermitent ignition..... <br /><br />Just .01 cents worth....

 

[johnkc]

Re: EFI Woes

saw this earlier and in my mind thought the same as schematic,but was too undecided to post .i'll go along with schematic now.