1975 Evinrude 135 bogging down HELP

[Phillabaum]

My engine is coming along although still having problems with getting high RPM after 2 or 3 short runs.
When I got engine did not run. Replaced stator and BAD rectifier and rebuilt the carbs. Ran OK for about 3 - 3 min runs then wont get up on plane. (wont accel past a fast idle). So I replaced the Power Pack $$$. I think it ran better today but after a long run. then shut down for about 30 min it did not have a hole shot at all. Shut it down and tried again. Finally got up on plane and ran to the ramp. So I stopped shut down and tried again. Slow hole shot again but not as bad. MY THOUGHTS. Acts like an engine suffering from vapor lock. or It might be overheating. I thought the impeller looked ok but it was not new.
1. could it be a vapor lock problem on a carb? (not fuel injected so it sould not be)?
2. Could it be a fuel pump problem that is only happening when its hot?
3. Could it be a coil problem that is happening when hot?(have not replaced those yet.)
4. Could it be a overheating problem? (OH MY)

Remember it runs GREAT when first on the water. (cold)

Compression 130 on all four. YEA.

 

[SparkieBoat]

Re: 1975 Evinrude 135 bogging down HELP

fuel pump or fuel line sucking air or tank vent clogged.

 

[Phillabaum]

Re: 1975 Evinrude 135 bogging down HELP

fuel pump or fuel line sucking air or tank vent clogged.

Tank vent is OK. How can I check to see if fuel pump is sucking air. And if fuel pump why would it only happens when hot? Remember its acting like vapor lock. But its a carb motor. Is it possilbe I am having a cooling problem? Thanks for reply, Great site.

 

[SparkieBoat]

Re: 1975 Evinrude 135 bogging down HELP

it is possible that you are having a cooling problem, lay your hand on the top of each head when it is acting up, if you cannot hold your hand there for about 3-5 secs without burning it, you are having a cooling problem. you need to test your overheat alarm and maybe replace your temp senders. also try pumping your fuel bulb when it is acting up, if this causes the motor to begin to run better, then you have a fuel problem.

 

[Phillabaum]

Re: 1975 Evinrude 135 bogging down HELP

it is possible that you are having a cooling problem, lay your hand on the top of each head when it is acting up, if you cannot hold your hand there for about 3-5 secs without burning it, you are having a cooling problem. you need to test your overheat alarm and maybe replace your temp senders. also try pumping your fuel bulb when it is acting up, if this causes the motor to begin to run better, then you have a fuel problem.

Thanks "sparkieboat". I pumped the bulb and did not help. No overheat alarm on the 1975. I just placed an order for the water pump repair KIT with all the goodies. I am thinking overheating problem. If that is not it its going to be the coils, fuel pump, or the cylinders are loosing compression when getting up to temp. But it is fun working on the motor just not the wallet. I will post an update when next tested.

1975 Evinrude 135
1970 Evinrude 18hp, Tore down for TOTAL rebuild, Machine work complete
1984 Volvo Penta, AQ125A, Complete rebuild. Not yet started

Phillabaum

 

[SparkieBoat]

Re: 1975 Evinrude 135 bogging down HELP

you should be able to install an aftermarket temp gauge or water pressure gauge on that motor, check compression and spark.

 

[emdsapmgr]

Re: 1975 Evinrude 135 bogging down HELP

When the engine bogs, maybe you don't have good spark on all 4 plugwires. Did you test each wire for spark when you had the engine problems? An inductive timing light is helpful for this test. You have not mentioned qualifying the timer base or the coils. The later engines have a voltage output minimum to qualify the timer base. You may find some good ignition troubleshooting at cdielectronics.com. Weak electrical components tend to fail once the engine heats up to normal operating temps. Does it run better when the engine is just started (still cold?)

 

[Phillabaum]

Re: 1975 Evinrude 135 bogging down HELP

When the engine bogs, maybe you don't have good spark on all 4 plugwires. Did you test each wire for spark when you had the engine problems? An inductive timing light is helpful for this test. You have not mentioned qualifying the timer base or the coils. The later engines have a voltage output minimum to qualify the timer base. You may find some good ignition troubleshooting at cdielectronics.com. Weak electrical components tend to fail once the engine heats up to normal operating temps. Does it run better when the engine is just started (still cold?)

Yes runs good cold. But then stop to fish and when I re start it wont open up.
WHAT do you mean qualifying the timer base or coils.
Did not find info at CDI for this timer base only other ones.
new STATOR, RECTIFIER, POWER PACK.
If its a timer base then the cost is going to park the boat for a while. Those other three items were not cheap and did not fix the problem.
As soon as I replace the water pump with the new kit I will try to see how to hook up my timming light while haveing the problem and not fall out of the boat.

 

[emdsapmgr]

Re: 1975 Evinrude 135 bogging down HELP

The timer base generates very small voltage when the engine is cranked. The later engines have a minimum voltage output spec- like .3 volts. I was not sure if your earlier model has a spec-it would have been in the CDI info. You need a special peak-reading voltmeter in order to read that signal. Factory service manuals have ohm test specs for all these ignition components. You may want to consider getting an original factory service manual: check out outboardbooks.com.. It helps to take a buddyout with you when checking the spark on the plugwires. Take the cowling off and run it fast enough to get it on plane.

 

[Phillabaum]

Re: 1975 Evinrude 135 bogging down HELP

OK this is what I have so far.
Went to lake and ran some tests. Ran good cold. Then stoped to fish and then boggs down. Hooked up a timing light and each cylider getting same spark. spark only drops in proportion to the rmp of the moter. ALL four cyl. do the same so I am confident I am getting spark. Now I am thinking fuel I already rebuilt the carbs when I got the motor and I feel confident I built them correctly (I have done several in the past) but you never know? Pumping the bulb does not change the results. So I turned off the auto choke and left the coke open. NO CHANGE. But this is the new findings.

IF I put it in gear and idel then slowly try to accelerate it picks up a little rmp then when I push the throtle to open it dies. BUT, If I while at idle slam the throtle it will accelerate and get on plane and stay there. PLEASE NOTE I did notice while wide open that the engine was trying to grab some more rpm every once in a while but would not get it. JUST A FAST BURST FOR A COUPLE KICKS.

I am thinkling getting to much fuel. or Head gasket when hot (I can touch the cyl heads and not get burned) . Or maybe fuel pump. LET ME KNOW YOUR THOUGHTS remember acts like it is flooding.

Evinrude 135
130 psi all cyl cold
NEW Starter, Stator, Recifier, Power pack, water pump, and Rebuilt carbs

 

[Phillabaum]

Re: 1975 Evinrude 135 bogging down HELP

OK anybody go a clue??????

 

[emdsapmgr]

Re: 1975 Evinrude 135 bogging down HELP

Usually a short burst of extra rpm's is a sign that one plug started firing normally again. A result of an intermittent/weak ignition component.

 

[lawn]

Re: 1975 Evinrude 135 bogging down HELP

I have the same symptons and I have timed it, checked fuel pump etc....funny thing is when it starts to bog down and i can catch it quick enough I can flip the choke switch and away I go... So I am inclined to believe it is lack of fuel and I am going to drill out the jets a tiny bit an see what happens.. I will let you know the results..........

 

[lawn]

Re: 1975 Evinrude 135 bogging down HELP

Drilled all four high speed jets 1/1000 an what a difference it made...Runs Terrific....

I have the same symptons and I have timed it, checked fuel pump etc....funny thing is when it starts to bog down and i can catch it quick enough I can flip the choke switch and away I go... So I am inclined to believe it is lack of fuel and I am going to drill out the jets a tiny bit an see what happens.. I will let you know the results..........