90 hp Chrysler motor trouble

[boater376]

I have a 73 silver line boat and a 90hp crysler motor!
I'm having troubles keeping it running. I can get it started but once I put it in gear it kills the motor. I've tryed just about everything and can't figure it out.

 

[emoney]

Re: 90 hp Chrysler motor trouble

Just in case you haven't tried "everything", how about sharing what you have tried and what more you know about the motor, like....

Compression? Spark? Fuel system to include from the inside of the tank all the way to the exhaust? When was the last time the carbs were done?

Things like that sure do help folks help you. Welcome to iboats, btw!

 

[TwoFish]

Re: 90 hp Chrysler motor trouble

Welcome to Iboats boater376.

Could you give a brief rundown of what you have tried? This will help people to respond to your problem.


Have you checked the compression and spark?

 

[jerryjerry05]

Re: 90 hp Chrysler motor trouble

The rpms???
The lower unit,check the oil for water/rust.
Sometime the bearings get siezed???
Was checking out a motor one day it would hardly turn over.
The owner was using 2 batteries to start it.
I looked and looked and even removed the head.
Finnaly a light went off and I checked the oil,no oil,just water.
The unit was shot!!Luckily I had another!!!

Like the others said post what you did?

 

[boater376]

Re: 90 hp Chrysler motor trouble

Well I tell you what this is my first year with a boat do I don't no much but I have tried letting it warm up for a while I've trIed choking it, and pumping the gas. I don't really understand it because it will idle fine but once you put it in gear she kills theodore instantly

 

[stubtail]

Re: 90 hp Chrysler motor trouble

When it dies, is it like turning off the key (possible electrical issue), or does the RPM continue to drop until it won't sustain (idle too low)?

 

[emoney]

Re: 90 hp Chrysler motor trouble

Ok, that's a much better place to start. When you say "tried everything", we're assuming you've done tons of troubleshooting, etc. Let's start at the beginning and some basic diagnostic questions. Do you own a compression tester? Cheap ones can usually be picked up for around $10.00 and I think we've all watched TONS of folks come on here, spend loads of money without running compression, to find out later that they had a shot motor. Get a tester, run the test and post your results here. Next, when was the last time the carbs where cleaned/rebuilt? Today's fuel and discount gas stations are providing lots of yucky stuff in our fuel and those tiny ports in the carbs can quickly get gummed up. Also, have a look at your fuel lines all the way from the carbs back to the tank. Older set-ups are NOT prepared for ethanol fuel like todays lines are. They can start to flake & crack leading to issues in the carb. So look it over really good and tell us what you've found. And finally, how's the spark? Again, an inexpensive diagnostic tool is a spark tester. You should have a nice, bright arc on all cylinders. Run this test and like above, post your results. If you don't own a Service Manual, now's the time to get one.

Compression/Spark/Fuel...that's all it takes to have fun with a marine engine (or any I suppose for that matter). There are TONS of incredibly smart people right here in the forum willing and more than capable of helping you through this entire process. However, you've got to help them help you. They can and WILL get you running and you'll be back on the water in no time. Post as many pictures of things that confuse you or specific parts/areas that you have questions about so these guys know how to answer. They may be smart, but they're NOT mind readers. Good luck and welcome to iboats!

 

[Frank Acampora]

Re: 90 hp Chrysler motor trouble

The most common reason for a Chrysler engine to stall when put into gear is too low an idle RPM. That's simple, but what is not simple is the cause of the low RPM.

SO: The first thing you need to do is Check the plugs and change or clean them. These surface gap plugs tend to foul quite easily, especially with the older electronic /distributor ignitions. This will always cause a hard starting/ stalling in gear condition.

Buy, borrow, or rent a compression tester. Check compression on all three cylinders (if the engine is prior to 1982) or four cylinders (if it is a post 92 90 HP.) Compression should be equal and high--within 5-10 PSI on all cylinders and up around 100-120 PSI. One low cylinder will allow the engine to start and idle nicely yet stall in gear.

Finally, check the idle speed--you do have a tachometer, don't you? Raise idle speed untill the idle in forward gear in the water is 700-750. This usually translates into about 1000-1200 RPM in neutral, but the only significant measurement is in gear in the water. To raise the idle use the slotted screw with a locknut on the throttle/timing tower. It screws into the cast piece that also controls throttle opening. Screw in 1/2 turn at a time until idle speed is correct. The lower unit should "clunk" when put into gear, but should not slam or crash. The control handle should be moved briskly until in gear. Do not try to "ease" it into gear. This will damage the drive dogs.

 

[boater376]

Re: 90 hp Chrysler motor trouble

It is kinda like turning off the key when putting it into gear. But we're are gonna try putting new fuel line on it and new spark plugs and try that first. There is no tach on it. Is there anyway of hooking one up or is it not needed? When you put it in gear it will grind until you actually get it in gear and then it wil clunk. Is it suppose to do that? I was also wondering. For some reason when ur trolling it keeping making a smaller clunking noise and kinda jerks alittle bit.

 

[Frank Acampora]

Re: 90 hp Chrysler motor trouble

I always recommend a tach as the first instrument on the dash. Not only will it tell you correct RPM and help to use the correct prop, butif read correctly it will warn you of impending engine damage. It is the most useful engine gauge you can have.

There is a Tiny Tach which can be used for setting up the engine but if your engine is pre-1978, you can buy a 12 pole tach which is still available.

Grinding when put into gear is due to moving the control handle too slowly, mis-adjusted shift linkage, or worn drive dogs.

If you are "snapping " it into gear--and this requires moving the control handle about 1/3 of the way-- then the shift linkage may be out of adjustment. Search previous posts for adjusting linkage.

If your engine has a distributor, then check drive belt tension. Too tight will cause shifting problems. The drive belt should deflect about 1/8 to 3/16 inch before a .010 feeler gauge (pressed into the center like a finger) bends.

 

[boater376]

Re: 90 hp Chrysler motor trouble

Ok I put new fuel line and gaskets on the carbs and spark plugs on it and she purs like a kittin. I don't think if has ever ran so good. Thank you for all you that helped me out I really appretiate all the help