1995 Mercury 175 XRI
serial #0G257838

Motor started cutting out at WOT, then it would act like it ran out of gas. Took it in, mechanic said fuel pump was not being given ground connect to turn on, but he couldn't find anything. Thought ECU might be going out or electrical. While he had it, it started working but he admitted it was not from anything he did. Next trip 2 miles from launch, acts like it runs out of gas and won't restart. Fuel pump is not coming on. Take it home and if fuel pump comes on, then motor cranks right up. Decide to send ECU off to diagnose and fix if needed.

So my ECU is headed to Dennis Hoffman, but a friend had me come over today and try his ECU. Nothing, pump would not come on. His did, but mine would not. Zero ground coming from ECU. Logic says it has to be issue from connection, but if we manually get fuel pump to come on, the motor still won't start. Fuel pump will be running, but motor still acts like it is not getting any fuel. Bubble is hard and I can pump gas through line.


Very frustrating. Great compression and spark per mechanic.


Any help?

Fuel pump driver in ECM could be going out or also if battery voltage drops below I believe 9.5 or 10.5 volts it will shut the driver off most of the times I have come across this problem it was the pump driver. And on swapping ECM's if it is not the exact same part # as yours they will not work there 4 different ECM for a 175.....OPTI

I hope you are right about the different ECU's not working. Maybe that still could be the issue. Even though its the most expensive fix, its also the one of the most definitive and that is all I want - fixed and back fishing.

I don`t understand why you didn`t send the ECU in to be tested first 75.00. Other ECU`s will work. You can search yourself with your ECU # and find compatible #. I have replaced the wiring harness on a few of these motors. Have also wired the fuel pump direct to work off of the ignition switch.

Originally, my mechanic wasn't sure what the problem was and it seemed to start working. But it didn't. Debated what to do next then a couple people suggested sending it to Dennis Hoffman in TN which I did. While waiting on that process, a friend told me he had an extra to come over and see if it would work. We tried that last night and it did not work. My fuel pump still would not come on when starting. We would wire fuel pump direct and while it was running, try and start motor but even though fuel pump was running it would not start and acted like it was not getting gas. Which is where I sit now. So fuel pump is not coming on via differnt ECU's, but even when we get it running by wiring direct, there still seems to be no fuel getting to motor. I don't mind bringing it to a mechanic, but I can't let him spend unlimited hours searching. He's got 6 hours now without any luck. Dennis said he should have an answer on my ECU by Monday.

You might want to clean the fuel pressure regulator. Surely the mechanic checked that hidden fuel filter in the U shaped hose coming out of the bottom of the VST to the fuel pump

Nothing is surely anymore. This morning I did go pop the cowling and I've got fuel coming out of fuel pump when I manually hook fuel pump direct with a pressure of 35-40. That's where my lack of knowing much ends. It seems fuel is coming out of fuel pump, but motor acts like it is not getting it. I mean it will not even attempt to fire. Just turns and turn without a hint of anything.

gonna disagree with OPTI here.. we have ran every ecu imaginable (150 ta 225's, even analogs) on all different horse power 2.5's jus for testin' purposes.. you would be surprised on tha difference with perimeters in 'em.. some 150's ran better ona 200 than tha 200 and so on....

yours sounds like it may be tha ground in tha "ecu harness"... only common part that would effect drivers, includin' injectors, when swapin' ecu's......... but who knows for sure settin' here ona keyboard..

dennis will probably figure it out for ya though..............

I hope. But heres where I get stumped. If Dennis says my ECU is bad and fixes it. I still seem to have a problem since the other ECU didn't work last night. That's the part that is such a mystery. Let's say Dennis says my ECU is good or says it is bad - either way he sends me back a good ECU. And the motor still acts like it isn't getting to fuel to fire??

Then what could causing the problem?

And if theres a mechanic within 2.5 hours of Houston who thinks they can help, let me know and I'll bring it to you asap. Not looking necessarily for free help. Just want to get back running again.

if tha fuel pump will run if ya put 12v's straight from battery, not from tha ecu. after testin', fixin', and/or replacin' tha ecu and know for a fact its good ta go thats when ya gotta look else where and harness is a main item... its tha only common denominator left really............

You talking ECU harness?

yes.. i'm sure dennis will check from cannon plug and into tha ecu while hes doin' his thing but tha motor side of tha cannon plug needs ta be checked also... that plug consists of several small pins that can get loose and/or disoriented ta tha extent of partial/intermittent/no contact............ don't have a diagram here right now but pretty sure all tha drivers in tha ecu operate from a ground comin' thru that harness..jmo.

I really don't know if this is even on the right track with your problem as I'm not anywhere near knowledgeable in mechanicism, but I have a 1996 200hp Mercury XRi and mine was doing pretty much the same thing last year. I would get WOT and then it would die, wouldn't crank, and acted like it was out of gas. Sometimes it would start with a hard start, other times it wouldn't crank for a few days. I changed my plugs, threw some sea foam in it, ended up having to change my starter in the midst of all this, and bingo, I haven't had a problem with it in a year. It cranks right up every time no problem and runs like a champ. The motor has always been well taken care of and serviced yearly, but I was at a point where I couldn't afford a mechanic and I did a few simple things myself. Like I said, I'm no mechanic, this may not even end up being anything similar to your problem, but I figured since I saw this post, I'd chime in with what I did. Hope this helps. May have been the wrong thing for me to do or I've jinxed myself and will have trouble tomorrow. Good luck!

The pins in the harness can get bent, had that happen on my opti computer.

what year model is the engine if it is an early model 200 EFI you may check the fuel hose for a plugged up screen the early ones had a screen in the you hoes going from the VST to the electric fuel pump