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ECM or ICM Problem Engine will turnover but not fire

justin_katko

New member
"I have a 4.3L Mercury EFI Eng

"I have a 4.3L Mercury EFI Engine. When I would go from Idle to full throttle it began to "bog" down and nearly killed the engine. I would put it back into Neutral and try it again and it was fine. I went through this cycle about 4 times, and finally on the fifth it died. The motor will turn over, but will not fire."
 
"What have you looked at so fa

"What have you looked at so far and why do you suspect the ECM or IC module?

I would suspect a fuel issue before an ECM or IC module issue. Loosen the gas cap and see if it starts right up next time this happens. If it does, the vent is clogged.

Check the fuel pressure (at key ON, idle, 2000 RPM and WOT) and change the filter(s) if they haven't been in a long time. Also, take a fuel sample. If the gas is old and has been in the tank for a long time, it's no good and should be mixed with a high % of fresh gas if there isn't much in the tank. Drain the tank and clean it out if the sample is really bad. If the sample comes out cloudy, set it aside and let the water settle out. If there's a lot of water, definitely drain it. By the time you add enough ethanol to eliminate the water, the % of alcohol will be too high for the long-term health of the fuel system. Remember- E85 is 85% ethanol and you don't want to run that in a regular motor. If anyone tells you to put "dry gas" in the tank, that's just an oddball name for gas with 10% ethanol.

Try putting some gas into the throttle body to see if it's fuel or spark related. If you have a timing light, you can check for spark. Also, make sure the coil wire is good and that it's plugged in completely. Look around and make sure all other plugs are in and tight. Look for loose ground wires on the rear of the motor and make sure the battery cables are clean and tight.

Also, open the motor box and turn the key to ON. There should be a 2 second fuel pressure priming cycle and you should hear a click followed by a buzzing sound. If you don't hear the click, you definitely won't hear the buzzing. If no click- look on the motor for three black relays- they may or may not be marked as to their funciton. You can swap them to find out if the fuel pump relay is bad. If the relays are all good, you'll need to do some voltage and ground tests. If you get the click and buzzing, go to the next paragraph.

To check the IC module for proper function, look for a purple/white wire on the distributor and find a place in the rubber seal where you can stick a regular stick pin. Once you're sure it's in contact with the metal terminal, attach the red lead from a digital multi-meter to it and ground the black lead. Set the meter to DC volts and crank the motor. You should see 1-2 Vdc on this wire. If you don't, you may have a bad pickup coil or star wheel (depending on which distributor you have)."
 
There are other sensors that c

There are other sensors that control the fuel pump on this system. If you do not have the expertise for working on this it is best to take it in to someone that does.
You could cause more damage than you have if you do not know what you are doing.
As with most things these days the average person can not lift the hood and locate the problem on a EFI system.
It goes without saying if it does not run there is a reason. It has shut down before more damage is done.
To try and make it run again without knowing the reason it quit is asking for trouble.
Sorry but if you want to play you have to pay.
Save the extra cost of replacing a part that could be damaged if you keep screwing around with the EFI system. Just take it in and get it over with.
 
"charli- didn't you mentio

"charli- didn't you mention an oil pressure sensor in another thread?

I agree- the shotgun method of diagnostics is a waste of time, money and effort. Eventually, you may find the problem but it isn't worth it to find it that way."
 
"I took a timing light to each

"I took a timing light to each plug wire where it attaches to the Distributor and each one checked out fine. I then checked down by the Spark Plugs and #3 & #4 are not sparking. At one point I saw an Intermittent flash, but not a steady flash like the other cables. I sprayed some Starting Fluid down the intake and it won't "spit" or back fire, just continues to turn over. Even if 4 of the 6 cylinders are sparking shouldn't I be able to get it to fire?"
 
"I don't know the service

"I don't know the service history of your boat but if you don't know it either, you probably need to do a tune-up. If you're not getting spark at the plugs and the wires look old, they are and need to be replaced. What have you actually done to diagnose the problem? Needing a tune-up and suspecting the ECM/ICM doesn't make any sense. What year is the boat, how long have you owned it, what has been serviced, etc?

Make sure the distributor cap is on correctly. If it's on crooked and one side is higher than the other, the spark won't get to the plug wire. If the wires are bad, well, you know what happens. What do the cap/rotor/plugs look like?"
 
"SO with all the above said I

"SO with all the above said I decided to take the boat into the Sea Ray dealer to check the problem out. They plugged it into the Diagnostic Tester and said the MAT Sensor code came up, which still did not explain the engine not starting. They check the ignition sensor, located within the distributor. They probed it and said it was bad, and was causing the problem. So, I hauled it back home and bought a new Ignition Sensor, Spark Plugs, and Rotor. Of course, no Start. I used a Multi-meter and checked the Voltage Step as the rotor turned. It was stepping 5V to 0V at each turn. I then pulled the Spark Plugs and turned over the engine and noticed that the spark was weak, and also the timing light was picking up intermittent flash from certain cylinders still. I then checked the Ohm value on each of the 6 ignition cables and the center coil cable. They all checked out fine. I checked the compression on each cylinder…all checked out fine. Stumped, I finally decided to replace the ignition cables for the heck of it, just in case they were loosing current. I went to the Auto Store and bought some High-Performance Mallory Cables and an Ignition Coil.

So I hooked up the Cables and still no fire. So, it wasn’t sensors, cables, fuel/pump/injectors, or combustion..???. Well remember that $11.97, 1969 Chevy Pick-Up Ignition Coil I bought back at the store….I disconnect the old one and hooked the new one up. Turned it over and it started right up! From what I have heard is that Ignition Coils are usually bad or good, not in between. It is either sending the high voltage to the distributor or it is sending nothing. Apparently the Coil was breaking down and not yet dead.

PS- Good thing the Dealership replaced my plastic exhaust drain plug for $103.00 to help me out with getting it running…may have been the most expensive drain plug ever!"
 
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