3.7 mercruiser problems

[JSavage]

Not that they don't persist but what can I expect from a $450 boat.

I've rebuilt the carb and now I get a pretty decent idle. Oh, wait.... the history.

It was last put to sleep in 2004 before the former owner went to Iraq.
I took it out of mothballs this spring. I instantly replaced all of the ignition parts from the plugs back to the coil, including the points & condenser.

It ran, but not great.

I just finished the Carb... It wasn't pushing fuel. Now it idles fine and when I throttle forward it jets the fuel into the carb. Problem is, when I give it gas when it's running, it stalls. Am I looking at a timing issue or a fuel issue? I'm trying desperately to sort this out before this weekends camping trip.

Not that it's relevant to this topic but in an effort to share information, I also put a starter in. Napa wanted $269 for this piece and I had a tough time finding it much cheaper. I took the MERC part number and cross referenced it and came up with an alternate part number for a Wilson built starter. The cost? $113 plus core. As I researched further, I found that the exact same starter is sold for 18 different prices depending on application, obviously the marine applications are the most expensive.

Just a good tip.

 

[JSavage]

Re: 3.7 mercruiser problems

Update:

Sorry for the lack of patience... I'm a little fixated on this problem right now.

I've been out this morning running it on muffs. I can put it in forward and it will "idle" with the prop in motion. The second I start to add fuel, the hesitation starts and it dies if I keep pushing. If I run the trottle to about 25% and start it, it comes to life easily. If I move the throttle to the rear without engaging the "reverse gear" (throttle only) It dies, just like forward.

 

[Big Boat Bay Buster]

Re: 3.7 mercruiser problems

DO NOT concider anthing BUT a marine starter or alternator for your boat.
I had the same engine with the same problem. Did you change the accelerator pump when you did the carb? Make sure the timming is on point.Do you know how to adjust the mixture screws? I found that if you adjust the mixture slightly rich it helps the transition from idle to part throttle.I think you also have a 'shift interupt' problem. You might need a new lower shift cable--it might be the cause of your stalling.This is what I did to eliminate my problem. It still had a flat spot when cold, but as soon as it got to operating temp it was good. There may be an adjustment on the pump shot cam, green color bar on top of carb. you may have a choise of holes to use to give it more of a sqirt.
Chris

 

[JSavage]

Re: 3.7 mercruiser problems

solved one problem. It appears that the filter in the fuel pump is just too far gone. It's the stone type and I removed it. I had already installed an inline filter before it. Now it idles up real nice with no problems.... except now I get a stall when going into reverse. I disconnected the interrupter and shifted into reverse. It didn't engage. Is that also symptomatic of the lower shift cable?

The starter I put in is identical to the one that came out... except for the name. It works sweet and again, it cross references to the mercruiser part number.

I did put a new impeller on yesterday. Is it possible I screwed up the reinstall? If the shift shafts were not lined up right, could I still get forward an neutral but not reverse?

 

[stonyloam]

Re: 3.7 mercruiser problems

Is it possible I screwed up the reinstall? If the shift shafts were not lined up right, could I still get forward an neutral but not reverse?

Depends on what you did. First things first. Raise the outdrive and look underneath. Is the intermediate shaft properly engaging the upper shift shaft as in Ziggy's photo Post #14 here: http://forums.iboats.com/showthread.php?p=2764600#post2764600 Does the shifter control handle move freely back and fourth? Did you have the whole outdrive off or just the lower unit? Should be able to figure it out.

 

[JSavage]

Re: 3.7 mercruiser problems

I just took a look. In N or R the dog is to port. In F the dog is straight. The shift lever moves freely. I only removed the lower.

 

[stonyloam]

Re: 3.7 mercruiser problems

I just took a look. In N or R the dog is to port. In F the dog is straight. The shift lever moves freely. I only removed the lower.

That is good, supposed to be straight ahead in F, 1 click to port for N, and 2 clicks to port for R. You are not going far enough to port to get into R. Does the intermediate shaft fit tightly into the bottom of the upper connector or does it move up and down. If it is a good tight fit you may meed to adjust your shift cable.

 

[JSavage]

Re: 3.7 mercruiser problems

It's fairly snug. I pulled the lower again and checked it for reverse, shich it has. As I reassembled it, I was checking for reverse and noticed that it was just a c-hair away from engaging. So.... how do I adjust that?

 

[Eric 3.7LX Alpha 1]

Re: 3.7 mercruiser problems

The lower shift cable may just need to be replaced.

The factory adjustment procedure is in the manual #6 section: 2 A-18.

The manual is in the Adults only section at the top of forum. #6 is for drive and #8 for the engine. They are free to download.

Eric

 

[JSavage]

Re: 3.7 mercruiser problems

so... I was working on the adjustment and still can't get the R to lock up. When I pull on the detached cable, I can get the prop to clack (almost engaged) but I can't get it to go all the way. The cable moves freely... I just don't know.

I reach under the drive an, with the cables detached, try to push the upper shift shaft all the way to port, thus moving the dog and engaging the prop. Well, the upper wont go all the way but the intermediate will. There is a little more play than I originaly thought.

Any thoughts?

 

[stonyloam]

Re: 3.7 mercruiser problems

can't get the R to lock up. When I pull on the detached cable, I can get the prop to clack (almost engaged) but I can't get it to go all the way. The cable moves freely... I just don't know.

Any thoughts?

Read this thread, especially Don's comments: http://forums.iboats.com/showthread.php?t=413495

 

[JSavage]

Re: 3.7 mercruiser problems

Sorry Stony. I was posting an edit as you were posting a reply. I reach under the drive an, with the cables detached, try to push the upper shift shaft all the way to port, thus moving the dog and engaging the prop. Well, the upper wont go all the way but the intermediate will. There is a little more play than I originaly thought. Is there any way to tighten that?

 

[Eric 3.7LX Alpha 1]

Re: 3.7 mercruiser problems

In that thread that Terry has linked, there are trouble shooting steps you should take which will pinpoint if the cable is at fault or if it is the drive. The link is out of the Mercruiser manual for the drive. There is no other way to reduce play without replacing parts.

Good Luck with it.
Eric

 

[JSavage]

Re: 3.7 mercruiser problems

I yarded the drive off last night, behind the bell house. It was full of dirty grease and there was some corrosion, especially around the shift slide and shift shaft lever. I didn't find any water but I figure that a 21 year old drive is bound to get a little water in there at some point... likely the cause of the corrosion. It wasn't bad but could have been just enough to stop the slide from fully seating.

The cable moves free and smooth, there is squat for play in the drive itself, the uni's are tight and I checked the slop in the shift shaft and it was almost nil.... I'll know when it goes back together if I've corrected it by cleaning the cable to shift slide union. That fit with my observations; that I can almost get engagement but it stops just short of locking up and the cables seem to be free.

I checked the bellows while I was there and I didn't find any tears or holes.

Still, any additional help or tips would be great. I've got to find a new gasket this morning and then it's off to greasy greasy, sweaty sweaty land.

 

[JSavage]

Re: 3.7 mercruiser problems

looks like I may have gotten it. I put the drive back together and now I have reverse when I pull the cable. We'll see if it stays true after I get the cables adjusted and installed.

 

[JSavage]

Re: 3.7 mercruiser problems

Every thing's fixed. Since I can't stand a dangling thread, with no solution posted, here's my method and result.

The summary....

I started with a no fuel and no reverse condition. I rebuilt the carb, replaced any fouled fuel filters, and purged the fuel tank. I had most of my carb back but with a dead spot with slow throttle, which I addressed later.

As I looked into the reverse problem, I found that my cables moved freely. I decided to pull the drive and check the slop in the intermediate shaft, the upper shift shaft, and the gears. I found the gears to be solid and that the upper shift shaft was just a tiny bit away from making the shift. As I examined the upper shift shaft mechanisms, like the shift arm and such, I found some corrosion around the place where the shift cable exits the bell house, at the shift arm. I cleaned it out, including the grease in the bellows, checked the universal joints, the gimbal bearing, checked the bellows for holes, and removed any corrosion. I reassembled with fresh gaskets, after greasing the uni's, and set about adjusting the cables per the manual.

I now have reverse, forward, and neutral as required.

I still had a dead spot on my carb, right at the beginning of throttle. After thinking about Big Boat Bay Buster's suggestion about moving the TB to Accelerator pump rod to a different hole, which I don't have (the different holes), I looked toward the book. During rebuild, I checked the distances of this rod and it met specs. What it suggested if it hadn't met spec, was that it could be bent or straightened until it did. This told me that I could adjust it by doing just that. So, I examined the problem up close and found the butterflies in the TB were opening before any fuel was dispensed, causing a lean stall. I straightened that rod, a little at a time, until I had the responsiveness I needed.

I now have a fully functioning engine and outdrive. Much thanks to everyone that helped. Even if your direction wasn't spot on, it gave me food for thought.

 

[IMPERIAL 1988]

I currently have a 1988 imperial with twin 3.7 fresh water cooled engine with about 600 hours on them. Knock on wood i owned the boat for two seasons now with very little issues. They both start and run great run at about 160 both engine. I dont beat the **** out them either keep both rpm at around 3500 when cruising. I readr all about these negative past pratices that everyone has had. I tottally agree it is all how you take care of any engine is what you will get on of it.

 

[IMPERIAL 1988]

I currently have a 1988 imperial with twin 3.7 fresh water cooled engine with about 600 hours on them. Knock on wood i owned the boat for two seasons now with very little issues. They both start and run great rll how you take care of any engine is what you will get on of it. un at about 160 both engine. I dont beat the **** out them either keep both rpm at around 3500 when cruising. I read all about these negative past pratices that everyone has had. I tottally agree it is how you take care of any engine will determine how it performs

 

[IMPERIAL 1988]

I currently have a 1988 imperial with twin 3.7 fresh water cooled engine with about 600 hours on them. Knock on wood i owned the boat for two seasons now with very little issues. They both start and run great rll how you take care of any engine is what you will get on of it. un at about 160 both engine. I dont beat the **** out them either keep both rpm at around 3500 when cruising. I read all about these negative past pratices that everyone has had. I truely agree it is how you take care of any engine will determine how it performs

 

[stonyloam]

It is best you start your own thread, just copy and paste into new thread, I THINK. That will work, and we can help you out.