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Engine will not start
Hi Everyone,
Has anyone had the following happen. When key is turned on the alarm does not sound as it normally does (worked fine last weekend). But then the engine turns over but will not strat. I bypassed the kill switch, the engine has fire, checked all fuses and breakers I could find (no bad fuses or tripped breakers). Has about half a tank of gas (checked with a stick to make sure). I have not checked the fuel filter yet or the fuel pump. I will work on that this evening (any suggestion on a quick check of the fuel pump). Everything ran just fine last weekend but yesterday no start. One thing it has done in the past is if I pull the throttle back quickly sometime the engine will die but starts back up without a problem. Any suggestions or ideas? Also last weekend was first time I ran it full throttle, 4,600 RPM 40.4 MPH in calm water. 41.6 MPH on top of a 2 foot chop. Maybe I shook some trash loose in the tank or fule system? After the hard run in the lake I slowed down in bayou for an oncoming small boat and the engine died but fired back up and I ran 3,500 RPM to no wake zone, ran fine at idle, then opened up again for about 2 miles to home. Ran fine even during idle speed through canal to home. |
Re: Engine will not start
I'm guessing it could be the fuel pump. A quick check of the fuel pump is easy. Turn the key into the ON position (not start), and you should hear it cycle up for a second or two to pressurize the line. Mine's an MPI, and I had the same issue, it ran fine one day, and the next day it was dead. Had to replace my fuel pump and the Mercruiser Cool Fuel system.
I might suggest if it's in your budget, have it checked out at a service facility that works on Mercruisers. You could have as you say "shook up some trash" going almost 42mph with 2 foot chop. |
Re: Engine will not start
Hi Chris,
Thanks for the info, I plan to check out the fuel system this evening. I will try to check out the fuel pump first. I have not put my eyes on it yet, the engine in this thing is way below the deck and there is not much room to work. I do hear something running for a few seconds after I turn the key off but have not figured what that is but will find out today. Also I planned to remove & replace the fuel filter and check the pick up tube in the tank. If I can will do all the work myself as we do not have a Mercruiser Dealer in town and boat is on the lift in my boat shed. If its not running will have to tow it to the ramp and winch it on the trailer. Also is the fuel pump something that can be purchased from Auto Zone, NAPA or is it a Mercruiser part? Will post what I find. |
Re: Engine will not start
Mine is a 99 and my fuel pump is in the tank. There is an access hole (about a 6 inch plug that pries up with a screwdriver) under the back bench seat. This should give you access to the top of the fuel pump.... That is, if yours is set up the same as mine. Not sure where to buy them, but there should be a part number on it that you can use to find out. I have had really good luck at O'Reilleys getting parts for me. They usually have to order them, but can usually get them. Good luck on the search!
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Re: Engine will not start
The fuel pump is on the port side of the engine, at the very bottom of the block, by the oil pan. It's underneath the square thing in this pic.
http://brucebullockmarine.com/mercury/images/454mag.jpg If you have the "cool fuel" system, this is what the pump looks like. http://www.mercruiserparts.com/images/mer/1589.jpg Quote:
For your own safety, as well as passengers, stay away from automotive parts with your engine. Yes they're cheaper, but is possibly destroying your Mariah and the potential risk for injury or maybe even something worse worth it? Personally, I'll always pay the extra $$ for marine parts. |
Re: Engine will not start
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Re: Engine will not start
Just got home from work and went out to work on it. Turned the key on and the warning buzzer sounded. Turned the key to start and if fired up like nothing is wrong. Shut it off. Turned key on again no buzzer. Engine just spins and does not start. Sounds like I have an electical problem not a fuel problem. Any ideas.
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Re: Engine will not start
Chris,
The buzzer is a completely separate system from the fuel pump. It gets 12V from the ignition switch and a ground from either the low oil pressure switch or the low drive oil switch in the reservoir. My guess is you are having issues with your ignition switch or have bad contacts in the large circular connector that connects the engine to the boat harness. I would start by removing and connecting this connector multiple times to ensure that you are making good contact. It may also be the 50A circuit breaker on the engine. Happy hunting. |
Re: Engine will not start
Hi Steve,
Just unplugged and plugged the connector a few times and that did not do any good. Ran out of daylight and the mosquitos were coming out so I called it a day. It has to be something electrical because when the buzzer works the engine starts. If the buzzer does not sound when the key is turned on the engine does not start. It turns over and has fire but no fuel. Its also strange all of the electonics work when the key is turned on. All of the gauges are live and the tach needle jumps even when the buzzer does not sound. I will try to study the wiring harness in the manual tonight and see what I can figure out and chase more wires tomorrow. I hate the thought of having to do anything with the fuel pump. From what I can see the engine would have to be pulled because I can not even touch it. I can reach the black box on top of it but can not touch the fuel pump. Hope it's a bad wire. |
Re: Engine will not start
Found your problem......ITS only MARCH! try it in May !!!!!!!!!!
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Re: Engine will not start
It's 80 degrees and sun shine here, our boating season is pretty much year round. So right now I am wasting sun shine. I am narrowing down the problem and it seems to be pointing to the ECM. Per the repair manual diagram the ECM controls the warning buzzer sensor and the fuel pump relay along with many other sensors and relays. If I turn the ignition to the on position and the buzzer sounds the engine will start. If I turn the ingition to the on position and the buzzer does not sound, I do not here the fuel pump pressure up and the engine just spins over but will not strart. It is not getting fuel. It does have spark in either situaton and since the spark is also controled by the ECM it make the ECM suspect. I am still checking all wires and connections but may have to have the ECM checked. Big problem is boat is not on the trailer it is on a lift in my boat shed and even if I get it on the trailer nearest service center is over 50 miles away. Trying to find a local mechanic that can test the ECM, may have one in our Motor Cycle Club. Will keep all posted on what I find.
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Re: Engine will not start
Just a thought, but have you looked to see if there is a fuel pump relay (by itself) If so, it could be as simple as the relay going bad.... I have seen them get a little spot of corrosion on them and not make contact. My apologies for the bad info earlier on the fuel pump. Aparently the 7.4 is set up differently than my 5.7.
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Re: Engine will not start
No problem on the info. The fuel pump relay is on top of the engine, I will check it shortly and try to find the warring buzzer sensor to check it. I talked to the mechanic I thought may have equipment to check the ECM but he does not. I will chase a few more things but it is looking like I will take it to dealer and let them go through it and fix what they find. They have a check up special for 225.00 plus parts they go through and check everything.
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Re: Engine will not start
I had a car that did that with the fuel pump relay. It wouldn't start for anything but if you pecked on it with something, the pump would kick in, and it would fire right up. the relay was over 100 bucks, so I took a chance on tearing it up (actually it was broken anyway, so no real risk) and took it apart. Took a little 320 grit sandpaper to the contacts in there, and used some terminal cleaner on it. Worked for another year until I sold the car! I guess it's still running to this day.
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Re: Engine will not start
Swapped fuel pump relay with another one that was next to it and nothing changed. Also checked the fuses again. All terminals have power with the ignition switch on and all fuses check good. I am still looking & checking. Tapped on everything that looked like it needed tapping on, even the ECM and nothing. Did not spend a lot of time on it today, had to mow the yard.
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Re: Engine will not start
Chris,
Did you verify that you have battery voltage on the Grey wire coming off the Fuel Pump Relay? You should be able to hear the fuel pump buzz immediately after turning the ignition switch on. I believe it runs for about a second or two to prime the fuel rail and then the ECM shuts off the pump until the motort starts running...after which it runs continuosuly. If you want to take the ECM and fuel pump relay out of the equation, you can remove the Fuel Pump Relay from its socket and using a short piece of wire jump the terminal with the pink wire to the terminal with the grey wire. You shoud now hear the pump run continuously. If you don't hear it then either the pump is bad or the wiring to the pump (Grey is positive or Black is ground) is bad. As you say, the pump is tough to get to. P.S. The sound that you hear when you turn the key off is the Idle Air Control valve. Steve |
Re: Engine will not start
Hi Steve,
Pink wire has power, jumped pink wire to grey wire and fuel pump runs. The ECM does not signal the relay to turn the fuel pump on. I checked the relay by swapping it with the spark relay and the fuel pump relay works in the spark socket. Put spark relay on fuel pump and nothing. Also checked the kill switch, it's working properly, shift sensor is working properly and can not find any problems with the ignition switch. I turned the ignition to on, moved the shifter and can here the relays clicking, except that the fuel pump relay does not click. Turned the kill switch on an off and same thing. With the ignition switch on I disconnected and re-connected the main connector from the boat to the engine and can here the relays click, except for the fuel pump, also the warning buzzer does not sound (buzzer is good). So I am back to suspecting the ECM and looks like I will take it to dealer and let them go through it. Befoe that I will find the pink wire coming out of the ECM and test it at the ECM to make sure it is not broken between the ECM and the relay, also I did not check the ground wire in the relay connector so will do that also. There's a ton of wires on this engine and none easy to access. I did fix one thing, the electronic compass was not working and while tracing wires behind the dash, found a broken wire. Compass works now. |
Re: Engine will not start
Sounds like you are getting it narrowed down at least. Hopefully that will save you some big cash in diagnostic fees. It's a shame it couldn't be something simple like a bad relay :( Best of luck getting it all worked out!
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Re: Engine will not start
Sprayed it with WD-40 and put duct tape on it and it still won't start. ;). Tried jumping the fuel pump to make it run, starts up will not stay running. Also when I checked the wires coming into the relay they are all grounded except for the pink hot wire. I talked to the mechanic at the repair shop today and as soon as I can get it on the trailer I am going to bring it to him and have him to go through it and fix what he finds along with doing the yearly service. The engine oil and drive oil are fresh so he does not have to do that part. The trick is going to be towing it to the lanch and winching it onto the trailer as have only driven it on the trailer, never had to winch it on. While it is in the shop I am going to have the seats in the cock pit re-upholstered except for the drivers seat as it is in good condition. Will have them done in white tuck & roll so they all match and look fresh. After that a wax job and hopefully I am done except for putting gas in it and cruising. No issues in cabin, every thing works, it's very clean and all upholstery is in great shape. Thanks all for the advise and help, it's just more than this old shade tree mechanic can handle.
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Re: Engine will not start
It was the ECM. Did not take to dealer did all the trouble shooting myself in the boat lift, was about 99% sure it was the ECM after all the testing. Ordered new one, changed out and it fired up. I learned a lot doing this myself and now know why dealer charges so much to work on one of these. Perfromed some other task while working on the engine, like change out the belt and re-wire the 12V batteries and system the PO had this thing tuned into an electricians night mare. Few things left to do as the isolater is bad and the on board battery charger is not working, will change them this week. Other wise all is working fine and boat is running great (knock on wood).
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Re: Engine will not start
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And thanks a bunch for coming back and posting what the solution to the problem turned out to be, so we can all learn from it. So many times on forums there is massive discussion about problems, but then the original poster doesn't ever come back to say what particular thing turned out to be the problem and what was done to take care of it. We don't learn all we could have from those threads. Just kinda leaves us all scratching our heads and wondering what the problem turned out to be.:confused: |
Re: Engine will not start
Chris,
Congrats on finally solving the problem. It's great that you stuck with it and the knowledge that you gained will only help you in the future. Happy Boating :) Steve |
Re: Engine will not start
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Re: Engine will not start
Folks I thought I'd continue on with this thread in that I have a 7.4L MPI, Z280, and my situation is somewhat similar in that the engine turns just fine but won't fire. After I let it sit for a week or so I try it and the engine actually fires for about 3 seconds and quits. I'm getting spark from the coil to the cap so the plugs should be firing. I have a clear fuel line and the fuel filter is not clogged, dirty or obstructed. I have turned the key on and off a few times to cycle the pump and still nothing. I took the breather off the throttle body and sprayed starting fluid in several times but still nothing.
What have I missed? Thanks |
Re: Engine will not start
When you turn the ignition switch to on position does the warning buzzer sound? Also have you checked the fuel pump relay, it is on top of the engine just in front of the distributor. There are 2 grey colored relays side by side, looking at them the right or front one is the fuel pump relay the left or rear one (depending how they are positioned) is the spark relay. They should both click when you turn on the ignition switch. If fuel pump relay does not click on and run the fuel pump for about 3 seconds and the spark relay clicks, switch the 2 relays around and turn on the ignition. If the fuel pump relay clicks when in the spark socket the relay is good. If the spark relay in the fuel pump socket does not turn on the fuel pump for about 3 seconds you have to do more trouble shooting. Let me know what happens.
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Re: Engine will not start
Hi Chris:
Yes, the buzzer does come on when I turn the key to the on position. I will definitely check out the relay switches as you described - thank you! |
Re: Engine will not start
You checked fire from the coil to the cap, but did you check fire coming through the cap? Rotor could be cracked or bad. Did you replace the plugs & wires and possibly get the wires mixed up? check timing, compression?
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Re: Engine will not start
Yes, I tested three or four of the wires on the cap by pulling and seeing if a nice spark displayed once the engine turned and yes, nice spark on each one. Did not replace the wires and plugs so they are all in the correct position. I haven't been able to check the two relays in front yet so hopefully those will prove to be the problem.
Thanks for your input |
Re: Engine will not start
O.k, I gave the engine another try and it did start, however, it felt and sounded as though it were running on 5 cylinders, couldn't keep an idle and smoked like crazy. Awhile back, before the problem of not being able to start the engine, I was out and about when my overheating alarm sounded. Got it towed, replaced the impeller, which was chewed up, checked misc openings and ended up replacing the risers since they appeared blocked. So I have two problems now; 1), very rough engine that smokes and 2), overheating.
Ideas? |
Re: Engine will not start
Just had my impeller replaced as it was also shot. The mechanic also found some pieces of rubber in a coolant line on the opposite side of the motor (Not sure where). he said many people don't check there for impeller parts and can cause blockage which in turn causes overheating. Hope that helps.
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Re: Engine will not start
Roger,
Have you checked your engine coolant temp and Intake air temp sensors and or their wiring? If one of these two sensors or their wiring was faulty your engine would behave as you described. |
Re: Engine will not start
Hi - the engine temp guage approached 220 so I knew I had to shut it down before the alarm sounded. Haven't checked the Intake Air Temp Sensors. What do I look for or, how do you test them?
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Re: Engine will not start
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Re: Engine will not start
You may wish to do a compression check. You say runs on 5, not to scare you,but you may have a blown head gasket, ask me why i would say that :(
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