'02 350 mpi hard to start

[Charlie D.]

Hi all, new user. I have an on going ordeal with my mpi engine. I have to engage the starter for 20 sometimes 30 seconds or more to get it to fire up. I've been searching for the problem but havn't found it yet. I checked the fuel pressure was a bit low ( a couple pounds ) changed the fuel pressure regulator and now the fuel psi is within specs. Didn't help the start problem. The first time I changed the dist, cap and rotor it cured the problem but only for the next half dozen starts. Now the dist. cap and rotor change dosent' really have much effect, still hard to start. The boat was originally put into service in Denver, I live on the gulfcoast, sea level. I contacted Merc and was told that doesn't matter. OK could it be a sensor keeping the engine from firing as it should seeing that the first owner didn't know how to flush the engine and burned the raw water pump up? By the way the pump fryed before any damage could occur to the engine. Sorry for the long thread, just trying to cover everything.
thanks
charlie d.

 

[Haut Medoc]

Re: '02 350 mpi hard to start

Welcome to iboats.....I don't know enough about your specific engine to be helpful, but if you can post your serial # if possible there are members here who will have some answers for you......

 

[Charlie D.]

Re: '02 350 mpi hard to start

thanks for the welcome
serial # om285804
mcm 350 mag
model # 4442067as

 

[Don S]

Re: '02 350 mpi hard to start

That sn is for your transom shield, here are your other numbers.

ENG: 0M320855 4442067PS MERCRUISER 350 MAG BRAVO MPI
DRV: 0M145044 5441500LS MERCRUISER BRAVO 3 2.20:1
TRN: 0M285804 6211001N1 MERCRUISER BRAVO TRANSOM

Do you have Mercruiser service manuals #31 Rev 1 and manual #36 Rev 1 handy?
Do you have a DVM and know how to use it?
Do you have a code reader of any kind?
Have you changed the spark plugs?
Have you done a compression test?
Are you getting good (Bright Blue) spark on ALL plug wires?
Have you checked the fuel filters for water/contamination?

 

[Charlie D.]

Re: '02 350 mpi hard to start

Don, I don't a Mercruiser Service manual, I have got a Chilton, I looked at a Mercuiser service manual at my local dealer, in my opinion the manual didn't contain very clear or precise 'suggestions', for lack of a better word. I sort of felt like the dealer was "holding back" with this manual. I know with GM manuals there are several per model. I do have a Digital Volt Meter and know how to use it. I have an auto xray 5000 code reader. I have changed the plugs, the spark is sort of white not really true blue. Compression is on the money, and I have changed the fuel filter several times. I should add that the engine has 190 hours on it. It has been slow to crank from day one with me. It runs and performs great at all throttle positions, oil pressure, and temp are on the money after it cranks, idles fine, very smooth, it's just a devil to get going. The previous owner flushed the engine on the hose, let his 12yr son put the rabbit ears on and fried the raw water pump. He tried to crank it again at a later date while a friend listened to the engine, the friend told him he spun a main bearing and he never tried to crank it after that. After questioning him about the engine, temp, oil pressure, sounds the engine made moments before he shut it down I concluded that he ran the impeller dry on the raw water pump and locked the pump up. When I purchased the boat and got it home that's what it was. I put 60 hrs on it last summer all the time trying to figure out what's making it so hard to crank.

 

[tommays]

Re: '02 350 mpi hard to start

If you get the REAL manual it will have step buy step for pretty much everything BUT it is not a training manual

For example it will tell you how to test for voltage drop when cranking

If the voltage drop is to much the motor will not start correctly i can go on but you need to test things step buy step so they can be ruled out and the real problem can be found

Tommays

 

[Zackman]

Re: '02 350 mpi hard to start

It has been slow to crank from day one with me. it after that.

Slow cranking will make it difficult to start. How is the condition of the battery and starter.

 

[Charlie D.]

Re: '02 350 mpi hard to start

Thanks for the reply guy's. BSman the batteries are fully charged and test OK. The starter motor amazingly still spins fast. Tommays, the manual I bought, and later returned was titled Mercruiser Shop Manual about $75 but as I stated earlier it was very vague, very little step by step anything. I also bought a Mercruiser Outdrive Manual for my Bravo 3 that is excelent in reference to step by step procedure. Is there a certain title made by Merc I could look for? One thing I havn't thought of which I think maybe you are making mention of is the voltage drop at the coil during cranking. I'll check that as soon as I get a chance.
Thanks again for the input

 

[Don S]

Re: '02 350 mpi hard to start

Here are what the OEM Mercruiser manuals look like.

While 31 may not be necessary for troubleshooting, it's the one you need for basic engine repairs, and trust me, the "How To's" are better in them than any of the aftermarkets., but you have to know how to use them. Especailly manual 36. It's not easy, but it has EVERYthing in it on troubleshooting.

Back to your speed of cranking. The MPI engines are a bear to start if not cranking fast enough. Some problem areas.
1. Wrong type battery...... you need a STARTING battery of the correct CCA for your engine. DO NOT use a deep cycle battery. They show a bigger voltage drop and will cause starting problems.
2. Battery cable size vs. distance. Too small a battery cable will cut down the voltage too much. You must have properly sized cables. Especially if you have a long run between battery, battery switch and engine. Both Pos and Neg. must be sized properly.
3. And I see this one a lot. Wing nuts on the battery cable. Throw them away. Clean the ends and use regular nuts and a wrench to tighten.

As far as you code reader, does it work? Did you have any codes?

 

[Don S]

Re: '02 350 mpi hard to start

One thing I havn't thought of which I think maybe you are making mention of is the voltage drop at the coil during cranking.

It's not the voltage drop across the coil that causes the problem, it's the voltage drop the ECM sees from all the sensors and the reference high signal the ignition module sends to the ECM. If it doesn't see enough speed, it won't allow the engine to start.

 

[Charlie D.]

Re: '02 350 mpi hard to start

Don I'm looking to buy the manuals now. I wasn't thinking computer controlled engine earlier, I was thinking precomputer. I can see where the voltage drop would "fool" the ECM. Thanks a million. As far as my code reader, I can't hook it up, the plug on my engine doesn't match anything in my auto xray 5000 kit. There again I was mislead by my local dealer, He told me that I could scan my system with any OBD 2 scanner, I bought the 5000 and can't hook it up with supplied leads. I contacted the company that makes Merc's scanners and they couldn't legally tell me "which wire went where" to make my scanner work, told me it would work but not how. As far as batteries I replaced both batteries with the same CCA's and type that were originally in the boat. The cables are original and I'm cranking on the marine cranking battery and not the deep cycle. The boat is a Chapparal Signature 240 and nothing mechanical has ever been done to it other than my replacing the impeller in the raw water pump. I don't have a problem using the manual I have an auto racing and boating background before and after computers. I have always done my own work with no problems in performance or reliabilty but this engine has me stumped. I'm sure manual 36 will help out.

 

[Don S]

Re: '02 350 mpi hard to start

Every boat owner with the knowledge to repair an EFI engine should get one of these from Rinda.
About the cheapest way you can go and still do all the tests and read all the info your ECM has in it.
It's slower than the laptop method, but one hell-of-a-lot cheaper,

Here is the info on it.

http://216.230.203.183/marine/marine.htm