Help please Challenger 2000 240 merc EFI won't stay running

[geoffc]

I was running the boat in the lake and it quit. It will start run for a couple of seconds then stops. I have replaced the lift pump, the mechanical pump and the external filters. Ir still won't run could it be electronic?
Any help would be greatly appreciated.

Geoff

 

[Tim75]

On the side of the vst, near the bottom is a bleed screw. Set a catch can. Turn key ON. Can you feel the pump in the vst running? If no- you found the problem. If yes, let the gas drain for about 2 minutes. Does it flow steady? If not, you found the problem. A stuck inlet float needle. Need to remove and disassemble.

There is black with yellow stripe wire on top of engine, aft of flywheel. This is the engine kill wire. Disconnect and test in the water. A chafed spot can cause your problem. Reconnect the wire. Check the emergency kill switch. Do you have the throttle guardian? Black box about 1x3x4 inch in the driver helm box. That can cause problems, too.

 

[geoffc]

Thank you Tim 75 I will give these a try.

Thank you very much

 

[geoffc]

I took out the drain screw at the bottom of the vst and with the key on i don't hear or feel anything from the vst, I just hear the lift pump clicking the flow of gas starts slow gets more steady then after the lift pump stops the gas flow stops.
I looked for the Black and yellow wire for the kill switch couldn't find it.
I attached a picture, is this the guard box you spoke of?

Thank you very much

 

[Tim75]

I took out the drain screw at the bottom of the vst and with the key on i don't hear or feel anything from the vst, I just hear the lift pump clicking the flow of gas starts slow gets more steady then after the lift pump stops the gas flow stops.
I looked for the Black and yellow wire for the kill switch couldn't find it.
I attached a picture, is this the guard box you spoke of?

Thank you very much

In the drivers box, that is the throttle guardian. On the engine, that is part of the ignition system. Can you unplug the black wire with yellow stripe? Test in the water.

You should be able to feel the slight vibration of the pump inside the vst. It should run as long as the key is at RUN. Also check the fuel pressure at the tire vale on top of the vst. If you can't feel anything, start with the wiring to the top of the vst. Only 2 wires. You may need a new pump. $50 from ebay, $400 from Mercury. Remove and disassemble. Not too difficult.

 

[geoffc]

I checked the fuel pressure it is at 30 psi while the lift pump is running, when the pump stops I get about 25psi. I also started the engine and the psi stayed at 25 psi. If I have to replace that pump do you have to take the vst off to do it?

Thank you so much

 

[Tim75]

Unfortunately, yes. Order the o-ring between the vst halves. No special tools needed, but a small bench vise will make it easier. 2 flat screwdrivers. Before all that, check the wires to the vst. Voltage, ground, connection quality.

 

[geoffc]

I checked the voltage to the pump it was 11.8v. I took off the vst and pulled out the pump. I put 12v to it and it ran quite well. Should I still get a new pump? It was definitely not working in the boat

 

[Tim75]

I checked the voltage to the pump it was 11.8v. I took off the vst and pulled out the pump. I put 12v to it and it ran quite well. Should I still get a new pump? It was definitely not working in the boat

Was voltage checked with engine running or off?

It should be about 13v with engine idling. Check voltage at the pump wires and each wire to ground. Does your vst have a connector plug or separate wires? If you have separate wires, polarity matters. The right way, the pump will make pressure. The wrong way give no pressure.

If you have the vst pump in your hand, can you test the pressure directly from the pump at 12V? Be VERY careful! Without the pressure regulator circuit, it should be more than 36psi, maybe up to 85psi.

 

[geoffc]

The voltage was checked key on not running. Can't check with engine running only stays on for 5 seconds. The pump has two wire leads. When I took the pump off it hadn't been touched so the wiring was correct so the polarity was correct. I haven't checked pressure on the pump does it need to be in fuel to make pressure?



Thank you for your help

 

[Tim75]

The ECM does not like to operate on low volts and when you hit the starter, it probably drops below 9V. Give it a charge and try it.

Since this is a fluid pump, not an air pump, yes it needs to be in liquid to build pressure.

Have you looked at the insulation on the wires from the trigger as they come out from under the flywheel? Have you checked the tps for function and adjustment? MANY threads here about it.

 

[geoffc]

I will try those thank you

 

[geoffc]

Hi I replaced the pump in the vst Fuel pressure goes up to 34-36 psi. Still the same symptom's starts right up runs 2-5 seconds and stops. I was trying to find the tps sensor could you point me in the right direction please. I have not checked the throttle gaudian yet how do I know if it is bad? I know the trigger is under the flywheel would the engine start if the trigger was bad?


Thanks for all your help

 

[geoffc]

I was doing some more diagnostics, there is a relay next to the fuse for the lift pump what does it control?

 

[Tim75]

I was doing some more diagnostics, there is a relay next to the fuse for the lift pump what does it control?

I believe relay controls lift pump.

While you had the vst apart, did you check the float needle and seat? The needle corrodes and sticks in the seat.

 

[geoffc]

I did check the needle and seat, I found the black and yellow wire and disconnected it and bam runs like a champ. Put the wires back together and it dies like it did before. What causes this? Is there a fix cause the motor won't turn off with the switch anymore.

Making progress thanks again

 

[geoffc]

I thought I had disconnected the throttle Guardian but I guess I didn't cut the right wire. I cut them all and reconnected black and yellow and voila running like a champ.

Tim75 I can't thank you enough. Thanks for hanging in there with me everybody.


Geoff

 

[Tim75]

I thought I had disconnected the throttle Guardian but I guess I didn't cut the right wire. I cut them all and reconnected black and yellow and voila running like a champ.

Tim75 I can't thank you enough. Thanks for hanging in there with me everybody.


Geoff

the throttle Guardian seems to cause more problems than it solves.

Glad you are running again.