Topic: Intermittent 1997 Merc 150 EFI problem

This topic has 7 replies, 3 voices, and was last updated 8 years ago by Tpop.

Viewing 8 posts - 1 through 8 (of 8 total)

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May 14, 2018 at 3:08 pm #312092

Tpop
Participant

Have had this happen about 4 times in the last 2 years and twice in the last week. Waiting our turn to leave during start of tournament. Everything seems normal(motor idling at correct rpm). Motor stops running and will not restart. Motor cranks but will not fire. Notice that when key is turned to on the pump in the VST does not come on. Can run a jumper wire from ground to the negative terminal on VST and the pump activates. Im leaning towards a bad ECU but wonder if anyone else has some ideas what the problem could be.

May 14, 2018 at 6:42 pm #312141

Bass Cat Boats
Keymaster

There are 3 relays – 2 for the up and down trim. The third is for the motor. Could be issue be the engine relay? Just a thought……

May 15, 2018 at 12:10 pm #312162

Bass Cat Boats
Keymaster

this is a new one to us…

May 15, 2018 at 1:05 pm #312180

BIGCATTER
Participant

Had this happen on my brothers rig . ( 87 Pantera / 97 200 mag efi ) ECU was dropping the ground circuit for the pump . — I just wired in a dedicated ” key on ” circuit and bypassed the ECU , which uses a driver to ground the pump . — Been like that for two years now , and still going strong . — Hoss

May 15, 2018 at 1:12 pm #312198

Tpop
Participant

Its my understanding that the pump shuts off after 30 seconds in a properly working ECU/VST. Do you leave “key on” when running engine?

May 15, 2018 at 8:41 pm #312219

BIGCATTER
Participant

The pump on the vst is the high pressure pump for the injectors . — The ecu uses a driver to ground the pump . — Common problem for them to go bad after several years of use . — If the pump shuts off you have no fuel pressure . — The system mixes oil with gasoline in the vst and then sends it to the injectors . — Took me about 20 minutes to wire in a fused circuit for the fuel pump . — Works like a charm . — Or you can take out the ecu and send it to Simons ( if memory serves me ) in California for repair . — If you opt to send it in , have them put new injector drivers in as well , as theyll probably quit next . — Much cheaper than a new ecu from Merc. — Hope this helps you . — Mark

May 15, 2018 at 8:48 pm #312238

BIGCATTER
Participant

Tpop wrote:Its my understanding that the pump shuts off after 30 seconds in a properly working ECU/VST. Do you leave “key on” when running engine?See my post above . — Shouldve responded to yours instead of just posting . — Sorry . — Mark

May 15, 2018 at 9:25 pm #312257

Tpop
Participant

Thanks for the info. When this first happened a few years ago I did wire in a toggle switch. Removed it when problem disappeared. Already contacted Simons a few days ago. A rebuild on the ECU is about $800.00.
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