1990 90HP Force Outboard starting issues

[Tonykilla85]

No luck on the 2 man rule... Had a few backfires when spraying fuel thru the carbs. I believe the control lever is the 1990 model 3500, it does not have tilt/trim.
I will try to get a pic up. Think I might give in and run her up to the local boat shop. Def. glad to have the exhaust tube back on. I'm thinking worst case is to have the carbs rebuilt, set & synced.

 

[Jiggz]

That is really unfortunate, with good compression, good sparks and properly timed it's amazing that it will not even start or sneeze. Have you tried removing the carb bowl, checking the float, needle and inlet port for proper operation? And cleaning them at the same time. It is really not that complicated.

 

[Tonykilla85]

Yes I have set the floats, and the carbs he been cleaned with new seals installed.
I was thinking last night, I have an extra fuel pump I am going to try prior to heading to the shop. I am not noticing any fuel oil spraying into the cylinders when the starter is cranking. I hate to get this far and give up! I was a little frustrated yesterday, needless to say..

 

[Jiggz]

If the fuel filter is at least 3/4 full after priming it and the carbs are operating properly it should still start even if the fuel pump is inop but only until the fuel in the filter rans out. Double check the fuel/air idle mixture screw settings. It is recommended to initially set them at 1 turn out from lightly seated, but in your case try doing it at 1 1/2 turns even 2 turns out just to see if it will even start. You should do this on all carbs at the same time. Make sure you are not referring to the idle screw at the bottom of the timing tower instead this is the fuel/air mixture screw, which is the brass screw located at the very front of the carb.

If it starts you need to adjust the fuel/air idle screw back where it starts but not less than 1 turn out. This is to prevent fouling of the plugs. You will adjust this again later after you set your idle speed properly. If your powerhead has the prestolite ignition system, make sure you are using NGK's BUHX plugs or Champs UL18V otherwise if you have the Thunderbolt, use the BUHW or L76V.

 

[Tonykilla85]

Well the fuel filter is more then 75% full that's for sure!
I will play with the screws and see if I can find a sweet spot when my help gets back from Florida in a few weeks.
I sure hope it kicks over soon! Thanks for all the advise! I will post again when I get a chance to test it out.

 

[Tonykilla85]

Update*********
I replaced the fuel pump and i'm getting her to backfire w/o spraying through the carbs. Does this sound like a timing issue? The top cylinder is at tdc and the flywheel tick(larger center) is set to the tick next to the carbs. I'm stuck!!!

Thinking the carbs or timing myself but no expert by any means...

 

[Jiggz]

It cannot be the carbs. If it backfires, it's most likely timing. There's a video on the sticky post on how to check the timing. Having the #1 cylinder on TDC is just the first step in the timing. The next step is to make sure the trigger timing plate (controlled by the timing rod connected to the timing tower and in synch with the carbs) is also at zero (as indicated by the flywheel tick mark) when #1 cylinder is at TDC and finally when the control lever is at WOT and the carb's throttles are at horizontal the trigger advance place indicated by the timing ticks on the flywheel should be at 28 degrees BTDC (This equals to 30 degrees BTDC dynamic). Please watch the timing video to make sure your motor timing is up to par.

 

[Tonykilla85]

Great I will check out the videos and hope to get her back up and going this weekend. Thanks again for all the help Jiggz... Next time I hope it's going to be a little easier!

Tony

 

[Tonykilla85]

I now have the motor timed.
The #1 cylinder is at TDC, The timing light is showing 30 degs when the boat is at WOT.
I am still not getting her to start!?
It looks like with the boat at idle the back flaps (2nd set) on the carbs are not open enough to let fuel into the cylinders?

 

[Jiggz]

The back flaps you are referring to are actually the carb's throttle which is used to control engine speed. The ones on the front are for the choke mechanism and are always at horizontal unless you activate the choke system and then they close 3/4 of the way. Try starting again with a 2nd person but this time hold on the linkage bar (between carbs that contols the throttles) and raise it up a bit to open the throttles while another person cranks it over. Actually, this is the purpose of the "fast idle" position on the control lever. It opens the throttles a bit without getting in gear.

If engine starts (and dies after releasing the bar) then it means you need to adjust the idle screw located at the bottom of the timing tower (screw it down to open the throttles for idling).

 

[Tonykilla85]

Ill try it out tomorrow evening Jiggz and post the results...

 

[Tonykilla85]

No dice...
Tried holding the carbs open at all different angles while cranking her, and she still don't start.
I went through and reset the carb floats to make sure they were set correctly.
Fuel bulb stays over 75% full. Have new fuel in the tank.
Motor is timed correctly.
Battery fully charged.
No backfire/ cough or nothing.
STUCK!!! :mad-new::mad-new::mad-new:

 

[Jiggz]

Can you verify if the spark plugs are at least wet with fuel? With these motors, if the carbs are presumed to be working properly, i.e. delivering fuel, even at cranking you will notice wetting of the spark plugs if it does not fire at all. If spark plugs are bone dry, then carbs are not working properly or fuel is not getting into the bowls. If the spark plugs are wet, then there must be no spark to attain ignition or combustion. Or if there is spark and the spark plugs are wet, then there must be no compression. All three are basic requirements to have combustion or ignition in the cylinder, i.e., fuel-air mix, compression and spark.

Another way to find out if you are getting fuel in the cylinder is with the wet test. Remove a spark plug (e.g. #1 cylinder) ball up a table napkin paper and placed it right in front of the spark plug hole about an inch away. Crank up the motor about two~three revs. You should see fuel-oil mix stain on the napkin indicating you have fuel mix getting into the cylinders. If no stain, it means you are not getting fuel into the cylinders.

Again, use an in-line spark tester to test for sparks in each cylinder. Validate you have good compression.

Re-post your diagnosis results.

Do you also have a wiring diagram of the system? Can you post it?

 

[Tonykilla85]

I found a issue today... I'm not getting any spark on the bottom plug. Would this keep it from starting or no? I am in the process for getting a used cdi box now. Compression is good and I am getting fuel to spray from the carbs. Its even back firing and smoking from the exhaust when I try to start her (When I am playing with the carb screws)

 

[Jiggz]

Getting fuel to spray from the carbs is a good indication but not necessarily means you are getting fuel into the cylinders. The reason for this is if you have broken reeds, fuel will still spray from the carbs but will not get into the cylinder because it just goes back out. The wet test is a fool proof test to indicate you have fuel getting into the cylinders. And you should test all cylinders.

Having no spark in one of the cylinders is not necessarily a show stopper. It maybe hard starting but it will eventually start albeit with rough and high idle rpm.

 

[Tonykilla85]

I will preform the wet test sometime this week/weekend. I ordered a new coil pack yesterday & it should be here by the 2nd.

 

[Tonykilla85]

I did notice when tuning the carbs on Sunday there seemed to be fuel coming out the (carb air intake side). Should fuel be dripping out or no? I will do the wet test regardless...

 

[Jiggz]

Normally, with fully working reeds, there will be a little fuel drip going out of the carb's mouth which is almost unnoticeable especially if the motor is running fast. Another thing, if you overchoked the carbs' there will be a little fuel drip coming out of the carb's mouth. Now do not confuse the overflow hole on the side of the carb which is an indication the bowl is overflowing due to improper float height settings. But this overflow comes NOT from the mouth of the carb but from a small hole on the side.

If reeds are not working properly, you cannot miss the amount of fuel spraying back out of the carb's mouth. In fact, with you motor having individual carb on each cylinder, you cannot miss the blow back if reeds are not working properly.

Do the wet test and post pics of the results. If two of the cylinders are not getting the right amount of fuel-oil mix (and you already proved one cylinder doesn't have sparks), there's no way the motor will start. Instead, all you get is a single fire which is not enough to sustain running the engine. And sometimes, this sounds like a backfire but it is actually just a single cylinder firing. And since the bottom cylinder is not getting any spark, any one of the remaining two cylinders having a reed problem will prevent the motor from starting. So it is most likely you have two different problems on at least two different cylinders preventing you from starting the motor.

 

[Tonykilla85]

Thanks for the info, I pulled the spark plugs out individually and have no fuel on the paper towel... Nothing at all!
So you would think the reeds are not working properly? I will try and replace them this weekend. Will there be any notifiable difference between a good reed and a bad one?

Thanks

 

[Jiggz]

Well, don't jump on the conclusion yet and start shelling $$$ unnecessarily. The next step is to dismount the carbs and check on the conditions of the reeds. Basically, perfectly working reeds will have no gap (although they say you can have like 0.10" gap) meaning if you put it up against a source of light you should not see light go through them. If there is little light, you can either replace them or try reversing or flipping them over first. Just make sure you use loctite blue sealant on the screws that holds them to keep them in place.

If the reeds are in perfect shape, double check each carb. make sure the idle ckts are clear and properly working. Personally, I would connect one carb (dismounted from the intake adapter) to the fuel line from the fuel pump outlet, prime it (while covering the other end of the T-connector for the fuel) and then blow the "mouth" with LP air (about 10~15 PSI) simulating air going through and see if there is fuel coming out with the air at the other end. This will ensure the carbs are working properly when you re-install them.

Another possibility there is no fuel going through the cylinder despite perfect reeds, is leaks in the crankshaft. If you have air leaks in the crank shaft, most of the air going into the crankshaft area and eventually into the cylinders would not have fuel oil mix in it since it did not all pass through the carb but instead from the air leaks.