1UZ into Boat

[converted]

Hey guys 99.9% there trying to get a start on the boat but there are a few things baffling me:-

The Engine is a 91 Soarer (crashed but motor undamaged). I removed it from the car and was running upon removal.

The loom was done by Sideshow from the club...he has been a great help unfortunatley he is a bit busy to see the boat till end April but the kids are hammering me to have it finished by Easter...ho-hum woer is me....heheh

• Anyway unusual situation where the battery voltage at my positive bus bar reads 12.4V.
• There are two brand new marine batteries connected via a brand new dual battery switch rated at 300A peak or 175 A continuous.
• When you try and start the engine it turns over and voltage reads 12.03V. The starter turns over quickly.
• When you try it again you get a small click from the starter and the dash goes dead and the pumps turn off. The voltage then goes to 2.5 - 3.1 volts. It then slowly builds up and after 5 mins of gradually coming up will read 12.35 V and the pumps work again as well as the dash.
• Im currently putting a charge on the batteries however as after the first attempt at start with the starter turning over OK Im thinking this is not the issue.
• I dont know if Sideshow grounds the ECU or the ignitors in his loom but I was reading this is essential. I have not checked to see if the case was ground to the engine just yet but will....and update this thread.
• Pump is a bosch 040 (the big one) for the EFI fuel rail, the other ECCO carby pump like a mini SU pump which just recirculates fuel though a small surge tank.

In addition to this....once running I will need to be able to momentarily cut the engine whilst Im engaging forward or reverse gear. The Mercruiser gearbox has straight cut dogs which needs the engine revs to be cut to engage them.

Now on the Mercruiser wiring diagram there is a switch which momentarily grounds the negative side of the coil of the carbied 350 chev.
Can anyone suggest what I can do to cut the engine revs to snick it into gear?
I was thinking of open circuiting the ground of the primary bosch fuel pump to lose pressure on the rail to drop the revs???...any other suggestions???

much appreciated, craig

 

[converted]

Ok due to the magic of this forum I have progressed a little.
I think I had a faulty relay in sideshows loom on the starter circuit, replaced it with one of the other two and then i grounded the ignitors (they originially had some resistance to earth) but by grounding the case..boy what a difference it made!
The engine fired almost straight away and did the noise frighten me heck (I wasnt expecting it to fire)......basically straight exhaust through the transom! The noise was mega...
Anyway I will get another relay tomorrow and replace the faulty one/s.

Also with the cut out switch to engage gears, do you think if grounding the ignitor casing made a differece with starting, do you think that maybe creating an open circuit to the case ground my cut the igntion ...ie will the ignitors be able to handle that sort of thing?

 

[Zuffen]

First up.

If Jim did it it's right. No questions.

You can check the grounding of the coils but agian "if jim did it....."

The battery voltage sounds like flat batteries.

If one battery has a bad cell it will take the second battery with it. My suggestion is use just one battery but have both charged. That will mean if the one you're using is dud you can always swap to the good one. Once you figure out they are both good hook em back up.

To engage gears the ski boat we use has a Rolco box and you only need to get down to idle to select a gear (with a slight crunch!) but if you wan to momentarily take the power off the engine I would cut the ignition or fuel injectors, but not the fule pump.

Best way to cut the power is (in my opinoin) to interupt the power supply to the igniters or the power feed to the injectors. I favour the latter as there's only one feed to interupt. I would use a relay that I could power off with a press button, not a toggle switch as it only needs a momentary interuption. If you get your timing right you shouldn't see the engine stall.

The injectors are powered by a thick black wire with an orange trace.

Good luck with it all.

 

[gloverman]

One suggestion I have is use a changeover relay to the ignitors or coil - when the relay is triggered it could drop the power supply. I would try just cutting supply to one first to see how that works , I have done some mercrusier that cut half the ignition. You may find that interupting the ignitors could cause a stall as the feedback loop may cut the injection pulse.

Good luck

Cheers

 

[converted]

do i also need to ground the ecu case as well as the ignitor case?