Mercruiser 5.7 Need Help With Timing

[gndultimate]

I had some hell these past couple of weeks with my boat. It is a 26' Glastron with a 350 Mercrusier 5.7. Some how my risers went and water got into all 8 cylinders. I immediatley took the boat out of the water. Now water was in all 8 cylinders and in the oil and valves. I was told to pull the plugs and pour tranny fluid down the carb. I did that. I stripped the motor down and had the heads tested and re surfaced and put every thing back together with all new gaskets risers and manifolds. Now We got the timing probably pretty darn good but she idles at 1100 nice, If you kick it down it stalls out. Now the problem is..... we put new plugs in she starts and runs great for a couple of minutes and then bogs down and dies. When we pull the plugs there is black all on the plugs and they look fouled. I clean em up and put them back in and same thing, runs great and bam same thing. Can anyone give me any advice Please!

 

[Don S]

Re: Mercruiser 5.7 Need Help With Timing

Why can't you guys ever post the YEAR of your 350's/5.7's, 4.3's or 3.0's. They do change things from year to year you know.
Also, do you have a points ignition, or ThunderBolt IV or V ignition.

 

[Bondo]

Re: Mercruiser 5.7 Need Help With Timing

When we pull the plugs there is black all on the plugs and they look fouled. I clean em up and put them back in and same thing, runs great and bam same thing.

Ayuh,........

Whatever you've got,............. It's running Extremely Rich.........

 

[gndultimate]

Re: Mercruiser 5.7 Need Help With Timing

I am sorry for the lack of info. It is a 1999. It has a distributor with electronic ignition. Does anyone know the degrees for the timing? Many people has said it is running rich, but what can I do to correct that. Is it a carb issue or timing issue? I do appreciate all the replys and help that I can get.

 

[Don S]

Re: Mercruiser 5.7 Need Help With Timing

EDIT. Info was for a carbed engine, not EFI

 

[gndultimate]

Re: Mercruiser 5.7 Need Help With Timing

I am not sure if it makes a difference but it is throttle body. How do I go about getting it right.

 

[Don S]

Re: Mercruiser 5.7 Need Help With Timing

I am not sure if it makes a difference but it is throttle body. How do I go about getting it right.

Well gee, don't you think it would have been handy to say it was EFI a long time ago, instead of saying you poured tranny fluid down the CARB then wondering if you had a timing or CARB issue? You don't have a carb.

What you need is Merc service manual #24 then you can get all the information you need to troubleshoot an EFI system.

 

[brooksdonald]

Re: Mercruiser 5.7 Need Help With Timing

I've got a 5.7L EFI (99 model) that I just had the longblock replaced on twice last month (by a certified premiere Mercruiser shop) It would run great for about 30 minutes and then start missing at higher rpms. It would also idle roughly. On the first block, we finally determined that the ignition module was heating up and malfunctioning. Once the ignition module was replaced, everything ran fine. However, the damage had already been done (cracked block) and water showed up in the cylinders. The second block (on Mercruiser's dollar) was a charm - engine runs great. The ignition module is about $110 and could very well fix your problem. It controls your timing and if that gets off, you'll see what you have described.

Good luck!