Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

[JXD]

So after a few weeks of slowly cleaning and rebuilding the fuel side of the engine, I'm at the point now where I'm stuck.

I spent the last day or so checking old posts on the forums but I don't really know where to go from here.

So far I have:
Rebuilt all three carbs
Replaced all of the fuel lines and fuel filters
Cleaned out fuel tank and added fresh fuel
Replaced sparkplugs
Replaced batteries

I'm definitely getting fuel in the carbs. When I remove the plugs though, I don't see any sign of fuel at all. Should I? What are my next steps to troubleshoot this? Thanks.

The engine is a 1990 Johnson 150 VRO

 

[Dhadley]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

Do you have spark?

 

[boobie]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

Have you checked your spark yet? Should jump a 7/16 " open air gap. Also how about the kill and/or tether switch?

 

[older]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

An engine needs gas, spark and air to start/run. Check the simple things first.

 

[kenmyfam]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

I'm on the "do you have a spark" team as well.

 

[cajuncook1]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

Hey JXD,

In order for the experience guys to help you out, please post:

Make:
Model number:
HP of your motor:

Even though this was given on another thread, this a new thread and it helps out a great deal.

You will see a lot of experience guys ask about compression, spark and fuel. (They are using a systematic approach to diagnosing an engine problem or problems....in this order)

C= compression ( if your compression is low are uneven between cylinders >10% then others checks don't matter until the that is resolved) (This is very important the previous owner could have run this motor and overheated and damaged the pistons or cylinders or the head gasket could have blown)

S= Spark (if your have problems with your ignition then you can have the cleanest carb and great fuel delivery but it will run bad or not at all) (Bad coil, spark plugs, points, condensors or even bad power pack assembly depending on the year of your motor.) **Check spark on all cylinders**

F= Fuel (if your carbs are not clean and fast/slow idle needle are not set right then it will run but like crap. If you have it set too lean then you run the risk of poor fuel/oil delivery and damage your pistons and cylinders then you run into the problem of C (poor compression from damage).You could have bad fuel pump or a leaking fuel system.

When you clean a carburetor make sure you get a kit and take out all of the core plugs, because gunk and junk and can block up the 3 tiny holes under the core plug for the slow speed idle needle.

So get a spark tester ($7), compression gauge($12 to $14), Feeler gauge ($6)

A service manual helps out tremendously, it gives diagrams and specifications and much more. ( These can be purchased here on iboats)

Just some suggestions to help you out and also help the experts help you out as well!!!

cajuncook1

 

[JXD]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

Thanks for all the replies. I tested the spark plug cables with a volt meter prior to all the other work but I will go out tomorrow and get an actual spark tester as well as a compression tester. I'll start with that and post the results.

The engine is a Johnson 150 VRO and the model number is J150TLESB

Thanks again for bearing with me. I used to work on car engines back in high school (many years ago) but nothing too complex. For some reason though, I have always been intimidated by marine engines. If it wasn't for this forum I would have never made it this far.

 

[milmat1]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

I'm new to Marne engines as well. And I have worked on about every type of gasoline engine made, But you are Right These engines are a different Animal ! They are very unforgiving if everything isn't exactly correct. Good Luck !

 

[JXD]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

Ok, here's what I found out today. I picked up a spark tester and an compression tester.

Spark:
I tested the spark on each cylinder and came up with nothing - no spark. So I went back to the kill switch, just to make sure. Sure enough, there was no continuity across the switch - so I clipped the wires and tied them together, just to see if it would fire. Still nothing. So I checked both of the kill switch wires for continuity - no problems. I'm thinking that the problem is on the engine side(?)

Compression:
Everything that I have read on compression testing says that I have to warm up the engine first. That's not going to work here, so I'm not sure if these tests are accurate or not. Maybe someone can help me there. Anyway, the compression on all 6 cylinders is between 65-70 psi. Seems quite low to me.

What's do you think should be my next plan of attack? I'm guessing that the low compression is an issue but that doesn't matter until I get the sparks to fire. That's where I'm stuck - I don't even know where to begin with the ignition system.

 

[bktheking]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

Check this for testing:

http://www.cdielectronics.com/downl...44 (1989-1991 150 HP Without Quick-Start).pdf

Don't know if it's a quick start or not, shouldn't matter for spark.

 

[jbjennings]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

Since all your cylinders are close to one another, I wouldn't worry about that just yet. You'll have to troubleshoot your electrical system. I'm not sure about your motor but I believe that putting the kill switch wires together will ground the circuit and kill the motor. I believe you should have spark with the kill wires DISCONNEcTEd. I could be wrong about your particular system, though.
If It's not a bad kill switch, you'll have to go through the system step by step. You'll need a manual and a meter.
good luck,
JBJ

 

[JXD]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

So here's the update:

I know that I'm getting fuel into the system because I pulled off the fuel line after the fuel pump and it is pumping fuel when I crank the engine. I still do not have a spark on any of the 6 plugs.

At this point I have replaced all of the spark plug cables and tested each for continuity. I have also checked all of the wiring for continuity and replaced any corroded wires with new. I have also removed and cleaned each ignition coil - all six test out fine.

I read through the OEM manual and I have performed these tests with the following results:

Ignition coil resistance test - passed on all 6
Charge coil test - passed
Sensor coil ground test - passed
Sensor coil output test - no reading - should be .3 volts or higher - perhaps this is my problem?

The power pack test calls for a "Stevens instrument" which I do not have. I was wondering if there was an easier way to do a test on the power pack.

At this point I'm a little stuck. Any ideas? Thanks!

 

[bktheking]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

You need a DVA to test the powerpack, in my first post I included a link to CDI which contains all the instructions to figure out the no spark issue as well, have a look.

 

[daselbee]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

Tow it over to Mims, and we will fix it right up. Both of us, and you will learn alot about it in the process. PM me if interested.

And jbjennings is correct. When you connected the two kill switch wires at the switch, you killed the ignition. Those wires must be open to each other for the system to produce spark.

 

[Backlash]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

Have you disconnected the two wires from the kill switch that you connected together? If not, do so. You'll never get spark with them connected.

 

[boobie]

Re: Carbs rebuilt, fuel lines replaced, tank cleaned out - engine still doesn't fire

One other trick you could try is, look on the mtr where all the wiring goes into the power pack. you should find a black wire with a yellow tracer on it. Pull the amphol connector appart and push the black/yellow wire out of it and then reconnect the amphol connector. What you are doing is by passing the whole boat wiring harness and just dealing with the mtr wiring harness. Actually this is the first step you do when trouble shooting with a good oem manual.