MerCruiser 165 250 c.i. GM Motor Starting Problems

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

Well the good news is I tore the carb apart, and I did notice that a few sections of the carb were loose. Which I'm strongly thinking right now that the whole problem could be with the carb. I'm going to get the gasket kit on Friday, and hopefully after it is put back together I'll put it on the water and see what will happen. I think this could solve some of the problems. I'm also going to put a new fuel line on as well from the fuel pump to the carb, and lets hope for the best right now. Now if there is still other problems with it in the water then we have the rest of the list to go through.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

Ok now we have a new problem. I rebuilt the carb, and changed the plugs on it. I put it in the water earlier and it ran just fine in the water. It moved and everything. Problem now is at home with the hose on the outer drive assembly it won't turn over at all. The fuel pump is working perfectly, and if I manually feed it gas it will turn over no problems at all, but won't keep running. Any ideas on this problem?

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

It's been a little bit since I've updated anything on this thread so here it goes. I got a new carb for the motor. It's made by Mallory, and it is having some issues as well. I bought a in line fuel pressure gauge that stays there all the time. The fuel pump is pushing between 4 and 6 psi. It stays mostly at 5 psi though. The ignition coil is in good condition the dist. puts out a painful spark (had finger on metal part of screw driver and didn't realize it. OUCH) Now the spark plugs do get fouled out after a while of trying to start the boat, and it has something to do with the auto choke sticking or something like that. Hopefully this explains the problem well enough to see what I'm talking about. If not I can try to give better details on the problem.

 

[Fishermark]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

You don't need a permanent inline fuel pressure gauge - and depending upon where it is, it may not even be safe.

Having read all of the above - I see you wound up buying a new carb. You say it is made by Mallory? New or remanufactured?

Did you ever get the tools needed for the ignition side of things? Did you ever do the complete tune up?

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

You don't need a permanent inline fuel pressure gauge - and depending upon where it is, it may not even be safe.

Having read all of the above - I see you wound up buying a new carb. You say it is made by Mallory? New or remanufactured?

Did you ever get the tools needed for the ignition side of things? Did you ever do the complete tune up?

The carb is re-manufactured, and the fuel pressure gauge is suppose to be mounted right by the carb from the instructions I read. The boat shop I took the boat to did a complete tune up on it. The only thing not changed is the rotor cap and interior parts. Everything else has been changed on it.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

Ok there has been new problems that have come up with the motor. Well they are still the same problems as before, but I'm well beyond lost now. Here is a list of what I have done to the motor as far as testing it goes.

Checked timing, and it is right where it is suppose to be. I can't remember right now where it is suppose to be cause paper is in boat and wet from the rain. I also pulled EVERY plug wire to check it for spark, and there is perfect spark. Also pulled the plugs to test for spark and each plug gets plenty of spark, and it does have the vacuum trying to pull the plugs back into place when trying to start motor. A friend of mine brought his dwell meter over and checked the dwell on the motor, and he said it is right where it is suppose to be. (I do trust him on this one cause he rebuilds motors for a living, and has done a great share of boat motors, and he only works on MerCruiser and Mercury motors) The carb is shooting fuel into the motor while trying to start it. The fuel filters are all brand new (carb and main) I have also installed the fuel/water separator on the boat, and it is installed correctly. Came with good directions with the arrows on the unit. The fuel pressure is sitting at 4 PSI, but it can go lower than that at times due to the battery charge. (It goes between those 2 numbers depending on how much charge is on the battery when trying to start the motor). Right now I'm basically completely stuck on what could be causing the problems with this motor, and I'm starting to get extremely ticked off cause I'm having a hard time figuring out the problems here.

I was also told that with this motor it has a rich fuel/air ratio or something like that and to pull each plug put 3 squirts of oil into each plug hole. Turn the motor a few times, put plugs back in, and let sit no less than 24 hours then try starting it again. Would that be a good idea or bad idea to try?

 

[ziggy]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

have ya done a compression test?

i'm suspicious of 6 psi for the fuel pump. 6psi is max . have ya got something other than the oem fuel pump installed? 3-6 psi is the norm.

have you tried running on a remote fuel tank? that would eliminate anything prior the fuel pump as being the issue...

have you looked through the trouble shooting guide in the service manual? there are several pages of flow chart for your condition..

some carbs can't be rebuilt. i don't know how you tell if it is successful though, other than it works right. also, i've seen multiple specs. for setting up the carb. (i assume a 2gc) are the specs set up to the specs in the mercruiser service manual?

 

[dirtyoldman]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

Ok there has been new problems that have come up with the motor. Well they are still the same problems as before, but I'm well beyond lost now. Here is a list of what I have done to the motor as far as testing it goes.

Checked timing, and it is right where it is suppose to be. I can't remember right now where it is suppose to be cause paper is in boat and wet from the rain. I also pulled EVERY plug wire to check it for spark, and there is perfect spark. Also pulled the plugs to test for spark and each plug gets plenty of spark, and it does have the vacuum trying to pull the plugs back into place when trying to start motor. A friend of mine brought his dwell meter over and checked the dwell on the motor, and he said it is right where it is suppose to be. (I do trust him on this one cause he rebuilds motors for a living, and has done a great share of boat motors, and he only works on MerCruiser and Mercury motors) The carb is shooting fuel into the motor while trying to start it. The fuel filters are all brand new (carb and main) I have also installed the fuel/water separator on the boat, and it is installed correctly. Came with good directions with the arrows on the unit. The fuel pressure is sitting at 4 PSI, but it can go lower than that at times due to the battery charge. (It goes between those 2 numbers depending on how much charge is on the battery when trying to start the motor). Right now I'm basically completely stuck on what could be causing the problems with this motor, and I'm starting to get extremely ticked off cause I'm having a hard time figuring out the problems here.

I was also told that with this motor it has a rich fuel/air ratio or something like that and to pull each plug put 3 squirts of oil into each plug hole. Turn the motor a few times, put plugs back in, and let sit no less than 24 hours then try starting it again. Would that be a good idea or bad idea to try?

1) Have you checked the point gap? Have you changed the points and condenser? If not, start there.

2) Have you set the dwell? While you are in the distributor make sure there isn't a bunch of slop in the distributor shaft by manually moving it back and forth.

3) Get a new strainer for the carb inlet and try that. That one has eluded me several times now with similar symptoms. Then take a line and pull fuel out of a can as was suggested earlier.

4) I still think you probably need to rebuild your carburetor. Taking the top off and spraying carb cleaner in there is not rebuilding it. Where is your choke set? Could you be flooding it? Were the plugs wet when you pulled them out?

 

[Fishermark]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

The boat shop I took the boat to did a complete tune up on it. The only thing not changed is the rotor cap and interior parts. Everything else has been changed on it.

There is much that is contradictory in those statements - you cannot do a "complete tune up" without replacing the rotor cap.

When you mention the "interior parts" not being changed - what do you mean by that? Thinks like pistons, crankshaft... THOSE kind of interior parts? Or do you mean the interior parts of the distributor?

If you mean the main interior parts inside the engine, then to be frank, it is confusing to even mention that.

If however, you mean the interior parts of the distributor... then again - if those were not replaced, then a complete tune up was not done.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

1) Have you checked the point gap? Have you changed the points and condenser? If not, start there.

2) Have you set the dwell? While you are in the distributor make sure there isn't a bunch of slop in the distributor shaft by manually moving it back and forth.

3) Get a new strainer for the carb inlet and try that. That one has eluded me several times now with similar symptoms. Then take a line and pull fuel out of a can as was suggested earlier.

4) I still think you probably need to rebuild your carburetor. Taking the top off and spraying carb cleaner in there is not rebuilding it. Where is your choke set? Could you be flooding it? Were the plugs wet when you pulled them out?

I ordered the Mallory carb off of iboats about 2 months ago. The choak is set to run the motor at 600RPM, and the plugs were dry, but had a gas smell on them.

There is much that is contradictory in those statements - you cannot do a "complete tune up" without replacing the rotor cap.

When you mention the "interior parts" not being changed - what do you mean by that? Thinks like pistons, crankshaft... THOSE kind of interior parts? Or do you mean the interior parts of the distributor?

If you mean the main interior parts inside the engine, then to be frank, it is confusing to even mention that.

If however, you mean the interior parts of the distributor... then again - if those were not replaced, then a complete tune up was not done.

It's the parts inside the dist. weren't replaced. I'm going to order them from iboats and get those installed as soon as they get here, and go from there with it. I still need to do a compression test on the motor.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

How do I check the dwell on this motor? I read in the adult section, and I'm completely confused on how to do it. I got the parts for inside the dist cap so I just have to get it all set up and give it a shot. I'm still waiting for a friend do bring over the compression gauge though to check that part of it. I also pulled a sample from the carb fuel bowl to check it for water, and there is no signs of water in there. I pulled that sample by making a little catcher that will fit inside the carb and by hand throttled the fuel to get my sample. I got about 4cc of fuel out of it. I used a syringe to make the catcher deal.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

Finally got the motor running on this boat. I ended up pulling the tank out of it drained it, rebuilt the carb, installed new point, condenser, dist. cap, new plugs, fresh oil change, and now she starts up with out any problems. It did have a lot of water in the fuel tank which was causing the problem. The PSI for the fuel is sitting now at 5PSI. But now I'm really working on getting the interior rebuilt which updates will be posted soon in the other thread for my boat.