5HP 1988 NS5B Won't Run

[bs_115]

Hi. I cannot get my 1988 Nissan to start. I have rebuilt the carburetor thinking this was the issue, but apparantely not.

History: I bought this motor last season, and it ran fine half the year. The last half of season i spent struggling to keep it running, by mostly fiddling with the carburetor/fuel system. I have rebuilt carb, and have fresh new gas, and brand new NGK plug, gapped to .039.

I am questioning the spark. It is there, but does not look very strong, and I am no expert.

I would like to verify my ignition coil. Can anyone tell me how to do this and what the expected readings should be.

I have tried in vane to get a service manual, and really want to get this problem resolved so I can get onto more significant boating season preperations. With the real boat. This is for my dinghy....

Any suggestions appreciated (with exception of bringing to repair facility), and i will promptly respond to any additional information requests.

Thanks,
Bob (new member to this forum)

 

[pvanv]

Re: 5HP 1988 NS5B Won't Run

The factory service manual is Part # 003-21035-1, $44.17, available from any dealer, including me. You need to diagnose the mechanical, fuel, and ignition systems, so as not to be guessing. The spark should be a hot blue. Ignition parts are checked using a good analog ohm meter, along with guidance from the service manual. What is the compression? Are you using the onboard tank, or the remote tank (for the NS5BS model)? If using the onboard tank, be sure that it has enough fuel to get to the pump (on the side of the carb). Does the plug appear wet with fuel after trying to start? If not, you may not be getting sufficient fuel. When you had the carb off, did you do a proper, complete, carb disassembly (including jet and emulsion tube) and a 4-hour soak in real carb dip? If not, the carb may have fuel varnish clogging it up.

 

[bs_115]

Re: 5HP 1988 NS5B Won't Run

Plenty of new fuel (internal tank).
Compression:80
spark: white/blue
plug: brand new, smells of gas slightly when removed, but not visibly wet.

Have tried starter fluid into carb, and into cylinder directly. No combustion at all.

Is there a way to isolate to fuel problem?

Maybe i missed something when rebuilding the carb.

 

[pvanv]

Re: 5HP 1988 NS5B Won't Run

I would definitely take another look at the carb. The rest sounds very good. Be careful with ether-type starting fluid, as it can crack rings.

 

[stefan_d]

Re: 5HP 1988 NS5B Won't Run

fuel pump diaphragms and gaskets (sell separately from carb "rebuild kit" and often really all that you need) love that ethanol....

also seen it (twice) that a small head gasket leak on the earlier engines would leak a bit of water into the cylinder (as things were warming up) and douse the thing after running for a few minutes... compression fine cold... check down the plug hole with a small flashlight after trying to start it (with the waterpump in the water) or after it dies, if you can see water/oil emulsion (white goo) on top of the piston then you have your answer.

 

[TOHATSU GURU]

Re: 5HP 1988 NS5B Won't Run

"I am questioning the spark. It is there, but does not look very strong, and I am no expert."

You really do need to stop until you get a service manual. With that in hand you can eliminate the ignition system as the source of the problem(or confirm it) and move on to the fuel or mechanical system.

 

[bs_115]

Re: 5HP 1988 NS5B Won't Run

***PROBLEM SOLVED***

WD-40 to the rescue. seems i dried things out in my cylinder head by using starting fluid. a couple squirts of WD-40 and i had combustion!!! Actually, with the starting fluid, i guess it was firing, but i could hear this whine (kinda like a fart), coming from carburetor. My guess is this was the pressure escaping due to dried out ring? and dried up cylinder walls? Anyways, she's running fine now, i just need to put it all back together.

-Tohatsu Guru - How much is a service manual? i paid $150 for this motor, and have put about another $100 into parts, and hours of labor. Do you think this motor will go for several more years? If so, i will buy a manual from you, sounds like you are trying to sell me one.

 

[bs_115]

Re: 5HP 1988 NS5B Won't Run

Tohatsu Guru - What I should have said, was thanks for the help, but i try to keep costs to a minimum. I'm so cheap, i didn't even spring for my 115 Evinrude service manual, but instead opted for a crappie Seloc for $25.
Is there a similar low cost service manual?

Also, I am very glad that this forum, unlike some forums I go onto, that they constanly say 'bring it to an authorized repair facility'.

So, THANK YOU all for the help, and BTW my compression jumped from 80 psi to abou 105 when i sprayed the WD40, and ran it for a while.

Bob S

 

[TOHATSU GURU]

Re: 5HP 1988 NS5B Won't Run

The factory manual is about $50.00 and is available from any Tohatsu, Mercury or Nissan dealer...The after market manuals should be avoided like the plague. The engine itself could last as long as 50 years or more. It is still in production, virtually unchanged, since the early 80's....It's one of those magical bullet proof engines that everyone talks about