Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

[rapier469]

I do not post on here much, but before I dig too deeply on my own figured I would inquire in here.

I just rerigged a used 1999 Honda 115 on my 19 foot center console. The motor came off of a friends boat that I am always on, and was running great. He upgraded to a newer Honda and thus I got some of his rigging supplies (harness, keyswitch panel) but had to purchase my binnacle and cables elsewhere as he reused those. Well the motor sat for a couple months on an engine stand and then I just mounted it a week or so ago and ran all the rigging.

I pulled the boat out of the garage on Sunday to start it up for the first time on the rabbit ears and unfortunately had some issues. Essentially, the motor starts and purrs like a kitten, but approx. 20 seconds later or so, dies like I shut off the ignition switch. I tried starting it with a little bit of idle throttle and it does the same exact thing, like clockwork.

I started doing some searching on here and online, however I keep coming up with the standard fuel system checks, filters, water in the separator, VST issues, etc. Before I dig into that, I want to make sure its not something simple and electrical I overlooked when I rigged the motor. I have a tach, trim, and voltmeter hooked up and all work, keyswitch does everything I am used to, beeps when you put it in the on position, and the motor turns over without and issue. Just continually dies like it is some sort of protective shutdown feature. Can you run these motors on the rabbit ears with a garden hose?

EDIT: Forgot to mention, I was having a hard time finding one of the older style Honda quick fuel line connectors, so I hooked up the line directly using a double sided barbed hose fitting as a temporary solution. Not that I think that is the problem, but it was something else I had messed with.



I am hoping someone posts in here something really simple, but any help is appreciated.

Thanks

 

[rapier469]

So I found some info on the VST that led me to believe that I had a stuck float pin. I drained the VST (no gunk or water, although the gas that came out of it was off color) and took the VST off to inspect. I pulled it apart and it was clean as a whistle. The float was operating without issue, and both low pressure and high pressure filters were clean.

Is the high pressure fuel pump supposed to come on with the key in the "on" position? Or only when the motor is cranking/running? I was getting good fuel pressure at the port in the high pressure pump plate, however i had to crank the motor to get pressure.

Overall, I am back at square one. I amost want to say its a big vacuum leak, but I checked all the obvious hoses without any luck. Also the fact that I can rev the throttle without a change would lead me to believe that its not a vacuum leak.

I took a crappy video with my cell phone to assist any readers on here.

 

[supwhoaday]

Re: Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

I have the same motor with the SAME problem! I actually just fixed the problem today. First of all, I would like to add that it could be more than 1 problem causing the motor to do that. I would check the fuel lines and fuel priming bulb first. All the fuel lines going all the way up to the fuel/water seperator should be air tight and not leaking on the line or at any connections you may have on the fuel line. From the fuel/water seperator going to the bulb and the bulb to the quick connect going to the engine should also be air tight. The low pressure fuel pump and high pressure fuel pump will not work correctly if air is entering from some where in the fuel system. I fried my high pressure fuel pump because air was entering from a hole on my priming bulb. These fuel pumps are not cheap and the air entering in the system will cause your pumps to fry. My advice is to keep pumping your priming bulb for a couple of minutes and see if you motor dies when you stop. It should die as soon as your VST is dry and doesnt have any fuel left.

 

[rapier469]

Re: Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

Since I did not have the original Honda fuel connector, I had been using a double sided barb fitting to directly connect the line off the fuel water separator to the engine. Today I switched it out with a clear inline filter to see if there was any air, which there was not. Does the bulb need to be between the fuel water separator and the engine? Or can it be further back in the system? I have mine mounted at the tank underneath the console and it remains firm while cranking and running.

Also, when I drained the VST, it was definitely full of fuel. I am guessing it would take quite a few minutes at idle speed to burn through whats in there and the motor always dies in like 10-20 seconds (havent kept track).

 

[supwhoaday]

Re: Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

You definitely have a fuel problem! Have you tried checking the low pressure fuel filter under the cowling right behind the VST and fuel pump? There is also a high pressure fuel filter on top of your high pressure fuel pump. Sounds like you're not getting fuel to the fuel rail and injectors. You will also hear your HP pump run when the key is in the on position but the noise is very faint. Try using a small removable fuel tank directly to your motor without the fuel/water separator. These motors already have a fuel/water separator filter right above the low pressure fuel filter.

 

[rapier469]

Re: Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

You definitely have a fuel problem! Have you tried checking the low pressure fuel filter under the cowling right behind the VST and fuel pump? There is also a high pressure fuel filter on top of your high pressure fuel pump. Sounds like you're not getting fuel to the fuel rail and injectors. You will also hear your HP pump run when the key is in the on position but the noise is very faint. Try using a small removable fuel tank directly to your motor without the fuel/water separator. These motors already have a fuel/water separator filter right above the low pressure fuel filter.

So this problem could be occurring despite the VST being filled with fuel? When I took the fuel system apart, it looks like as long as there is ample fuel in the VST, the high pressure pump gets fuel, and thus the rail gets fuel.

Based upon what you are suggesting, it sounds like a problem with the low pressure pump could cause this despite the high pressure pump receiving fuel?

Just looking for some clarification here...

Also, is it possible for air to get trapped in the rail? Since its a regulated system with a return, I am guessing no and that any air in the rail would be cleared out during cranking... but just a thought...

 

[supwhoaday]

Re: Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

There is no way to tell if the VST is full when engine is operating. Look to save you a ton of headache, hook up a fuel pressure gauge to the HP fuel pump on the service bolt(bleed bolt).If the fuel system is operating properly the pressure should read 38-46 psi at idle. If you simply do not have the tools you can check the HP pump another way. Take the HP pump off and hook up 12v power directly to the pump. Make sure there isnt any fuel left in the pump before doing this! You can hear the pump operate when 12v power is hooked up.

Air will be pumped out the fuel pressure regulator but also back in if there is a vacumm leak some where. This is bad for your pumps and poor engine performance as you stated!

 

[rapier469]

Re: Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

There is no way to tell if the VST is full when engine is operating. Look to save you a ton of headache, hook up a fuel pressure gauge to the HP fuel pump on the service bolt(bleed bolt).If the fuel system is operating properly the pressure should read 38-46 psi at idle. If you simply do not have the tools you can check the HP pump another way. Take the HP pump off and hook up 12v power directly to the pump. Make sure there isnt any fuel left in the pump before doing this! You can hear the pump operate when 12v power is hooked up.

Air will be pumped out the fuel pressure regulator but also back in if there is a vacumm leak some where. This is bad for your pumps and poor engine performance as you stated!

The pump runs when an external 12V is applied. I redid my fuel line setup to eliminate the fuel/water separator temporarily. I am running a fuel line directly from the tank to the primer bulb facing vertically right below the engine. Seems to pump fuel and get very firm, possibly more than before. I am going to attempt running the motor like this and see if it makes a difference. I will report back with my findings.

 

[rapier469]

Re: Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

Well I started it up today with the same disappointing results. I had found one thread talking about a BF115 with similar issues and someone had mentioned something about a bad fuel pressure regulator. I pulled the plugs afterwards today and some of them were slightly wet. Since I wanted to quantify what kind of fuel pressures I was seeing at the outlet of the pump, I guess I will be looking for one to borrow.

If I am getting appropriate fuel pressure I will have to start looking elsewhere, as the fuel on the plugs is starting to make me think it has not been fuel related all along. Is there something that could be killing spark after starting?

Also, I was talking with my buddy about the marina who pulled the motor off his boat and they had checked compression and did a leakdown test on the motor prior to pulling it. All was fine, however it made me wonder if there is a fuse or something they disconnected prior to doing the compression check that is killing spark and/or fuel to the engine...

 

[rapier469]

Re: Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

Well I think I am on to something. I was out on my friends boat today with the newer Honda on it and had him key over the ignition while I listened for the fuel pump just for a comparison. As everything I have read has suggested the pump turns on and runs for approximately 2-3 seconds and shuts off.

What I realized is that despite the fact the the pump runs with 12V directly applied to it from an external source, it is not running with the key in the on position. It apparently must run when the key is turned that extra bit to the cranking position as I get fuel pressure at the high pressure test port, but when cranking is completed and the engine starts (the key is back in the "on" position") there is no more fuel pressure which explains it consistently dying after 10 seconds or so.

Anyways it sounds like there might be an issue with the relay that runs the pump? Is that the main relay at the front of the engine?

Next thing I am going to do is "hot wiring" the pump to see if the engine continues to run. We shall see where that gets me.

 

[supwhoaday]

Re: Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

Did you ever fix the problem????

 

[rapier469]

Re: Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

Did you ever fix the problem????

I just got a new main relay in yesterday and hooked everything back up. I did not have the time to drag the boat out of the garage to fire it up, but when I turned the key over, the fuel pump cycled for 2 seconds like it is supposed to which is promising. I am going to fire it up this afternoon and will report back. At this time, it is looking like it was the main relay all along.

Also, I never added some additional information I discovered after my previous post. I took a multimeter to the wires at the relay using the wire diagram and with the key on, I was getting 12V at the input wire to the relay for the fuel pump, however I was only getting about 1 volt out at the fuel pump's blue and yellow wire. Now it appears I am getting the correct voltage to the fuel pump from the relay.

 

[rapier469]

Re: Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

Well,

It turns out it was the main relay. I drug it out of the garage yesterday and it fired up and remained running for the first time. So it appears the issue is resolved.

 

[supwhoaday]

Re: Rerigged with Honda 115... keeps dieing on after 20 seconds on startup

That is good to hear you will be fishing soon.