1995 Mercury 175 EFI fuel injectors flooding intake manifold.

**RAnger0395** · 05-06-2023, 08:30 PM

I have a 1995 175 mercury 2.5 EFI which i just put in new CCMS reeds. I pull the injectors out and inspected them, put new o rings on the the seals still looked good so i left them on. So before i put the intake manifold back on I made sure no leaks were present with the induction manifold off and the electric fuel pump running for about 20 secs. No leaks were present. So i installed the gaskets put everything back on. Went to start the engine it would crank but not turn over. I smelt gas and seen gas was poring out of the Butterflys. I took the induction manifold off and gas came pouring out. when the electric fuel pump was running all the fuel injectors were spittting out a straight stream of fuel. I am guessing that is not supposed to happen when the electric fuel pump is running??? So why is all the injectors spraying fuel when the electric fuel pump running?? Thank you for any help!!

**OnPad** · 05-06-2023, 09:21 PM

I believe that the injectors are driven from ecu, which gets its timed signal from the trigger.
Bad ecu, trigger, or wiring?
There's tests for trigger, and ecu drivers.

I had a fitting break at the top of manifold, and it filled the engine with fuel, but not through the injectors.

**RAnger0395** · 05-07-2023, 03:39 PM

Yes The injectors are opened andclosed electronically by the Electronic Control Module (ECM). I know the trigger is good i replaced it last year plus i tested the trigger according to the Manual. I guess my main question is should the Injectors be firing if only the Electric fuel pump is priming when the key is turned on and not cranking?

**OnPad** · 05-07-2023, 04:10 PM

Originally Posted by RAnger0395

Yes The injectors are opened andclosed electronically by the Electronic Control Module (ECM). I know the trigger is good i replaced it last year plus i tested the trigger according to the Manual. I guess my main question is should the Injectors be firing if only the Electric fuel pump is priming when the key is turned on and not cranking?

I surely would think not.

Maybe your injector harness is jacked up?
Maybe you had a major meltdown in ecu?

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**OnPad** · 05-07-2023, 04:48 PM

This is where I had issues. The brass fitting came loose from brass plate at silver solder joint. This creates a no start, and fuel to be dumped unregulated into manifold.

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**Jim Speros** · 05-07-2023, 09:36 PM

Odd issue. What was the purpose of inspecting injectors. Looking at them tells little. Did you send them out of service?
When you say straight stream. Like a squirt gun. Not a fan spray? Seems unlikely they all sudden got dirty. Debris will make them piss and weep.
If they are all spraying a nice fan pattern I'd be looking at wiring but not sure how all six could get power to them at once. Seems likely you'll be pulling injectors out again and sending them out for service and flow test.

**David - WI** · 05-07-2023, 10:26 PM

If the the thing has been sitting, the fuel in the injectors oxidizes and gums up. The solenoids in the injectors have more than enough power to open the injector but the return springs aren't strong enough to close them... so they leak when there's pressure.

Send the injectors out to Brucato or Kinsler or someplace and have them cleaned and flow tested.

**RAnger0395** · 05-08-2023, 05:03 PM

Odd is right!!! I understand that a visual inspection really does nothing!! I figured while i had the manifold off i would replace the O rings and make sure the seals were not bad. I tested the injector harness according to the merc manual and the harness is in specs. I will be having them flow tested this week. I have a gut feeling that my ECM is the cause!! but i hope im wrong!!

**David - WI** · 05-08-2023, 06:04 PM

Why don't you unplug an injector and see if it leaks like the other 5?
(Or unplug them all.)

**RAnger0395** · 05-26-2023, 08:16 PM

ok I have my injector problem fixed after back flushing all the injectors a bunch of black crud came out, spray pattern is now right, After installing everything back and i now have a crappy idle in neutral!! here is what has been done so far.

Compression on all cylinders is 119-120 psi
TPS set at .250
Fuel pressure 36 psi
ccms reeds
head gaskets replaced.
exhaust divider plate gasket and seal replaced.
cdi coils replaced last year
Trigger replaced last year
stator check to specs
trigger check to specs
replaced all bleed lines and all fuel hoses.
spark plugs are new
fuel filter is new

i did a cylinder drop test and when i pulled #5 plug wire the idle smoothed out completely!!! I talked to a merc tech nearby and he said the look at the Flywheel and stator again. So today i pulled the flywheel off and it has chips in one magnet. the stator looked good couldn't tell if any rub marks on it.

I also disconnected the top yellow wire to the voltage regulator and the rpms shot up. is it possible that my flywheel causing the bad idle now? what am i over looking?

Thanks

**OnPad** · 05-26-2023, 08:37 PM

Fuel lines?
Pulse pump?
Check valves in tank/bulb/vst?
Clean vst?
Temp sensor?
Map sensor?
Dva electrical, and bias, sb's?
Ohm coils?
Timing?
Oh, and the screen in regulator, and u shaped fuel hose.

**RAnger0395** · 05-26-2023, 08:54 PM

yes i did all of that just didnt post it, i guess my main question would be is why would # 5 cylinder smooth out the idle like that after pulling the plug wire.