restoration of 1991 VIP and engine upgrade inc conversion from spitfire ignition

[VIPUK]

Hello guys,

I'm really hoping someone can help as after 2 years and circa £20k GPB I have a boat that looks great but won't run!

It's a 1991 VIP with a 4.3 engine. When I bought the boat I was told the engine had been hydralocked and so wouldn't run. After several failed attempts to free up the original engine we opted to 'upgrade' to a (approx) 2001 Vortec short engine. This meant switching to an electric fuel pump and required a new inlet manifold, so we got an Edelbrok Marine Performer intake and an electric fuel pump.

I passed this over to local marine engineers (but here in the UK that's a loose term) and they replaced the manifolds but said they couldn't make the spitfire system work and wanted to replace it with a distributer system - which I agreed to.

Long story short - everything is new but the boat cuts out (slowly) after the auto choke turns off once it gets warm. They asserted it was the carb so i've replaced the original Holley with a new Edelbrok - to no avail - exact same problem. It'll run when cold but won't idle once warm and it's reluctant to start once warm....

I'm not convinced that they entirely know how to convert from pre-vortec to vortec or spitfire to distributor (for example they got me to buy a new rev counter when in fact they just hadn't identified the required wire in the old loom)

Can anyone please tell me what is going on or suggest a fix?

Thanks in advance.

 

[GA_Boater]

What motor? It doesn't matter that it's in a VIP.

Mercruiser, Volvo-Penta or ?????

 

[VIPUK]

What motor? It doesn't matter that it's in a VIP.

Mercruiser, Volvo-Penta or ?????

Originally it was an OMC - but the replacement engine is a converted road engine from USA. As far as I can tell only the leg remains OMC - the rest is new.....

 

[VIPUK]

but the new engine code is transferable to a mercruiser...

 

[Lou C]

The engines were always (till Merc started making their own) GM marine based on Chevrolet car & truck engines.
Have the “engineers” done diagnostics to determine why it’s not starting? Lack of spark, fuel or other cause?

 

[Bondo]

Originally it was an OMC - but the replacement engine is a converted road engine from USA. As far as I can tell only the leg remains OMC - the rest is new.....

Ayuh,..... Welcome Aboard,...... Like Lou says, you need some diagnosis, before anybody can figure out a fix,.....

It "Sounds" like a lack of fuel,....
Any restrictions in the tank,..?? Lines,..?? filter,..??
Which eldebrock carb,..?? if the 1409, that's a solid carb,.....

'n I moved yer thread to the OMC forum, as the "Spitfire" threw me off in the Merc forum,.... Merc would be Thunderbolt ignition,.....

 

[GA_Boater]

Ayuh,..... Welcome Aboard,...... Like Lou says, you need some diagnosis, before anybody can figure out a fix,.....

It "Sounds" like a lack of fuel,....
Any restrictions in the tank,..?? Lines,..?? filter,..??
Which eldebrock carb,..?? if the 1409, that's a solid carb,.....

'n I moved yer thread to the OMC forum, as the "Spitfire" threw me off in the Merc forum,.... Merc would be Thunderbolt ignition,.....

Thanks, Bondo. I was thrown off by the OP. LOL

 

[VIPUK]

Thanks for the replies so far - No the 'engineers' did not diagnose the issue but we have this morning - its a very very weak spark after the choke turns off....

 

[Lou C]

Electric choke, which needs constant 12v to open, if connected to the ignition coil can cause that. In fact the instructions for Holley and Edelbrock carbs tell you not to wire it that way.
The electric choke should be connected to the AC tap terminal on the alternator, depending on which alternator you have. Disconnect the positive lead from the auto choke wire the choke open and run the engine at idle. Use a voltmeter to find a terminal on the alternator that supplies charging voltage only when the engine is running. If you use one that has voltage all the time that the ignition switch is on the choke will open too soon. I actually prefer the old style manifold heated choke on my Quadrajet. They seem more reliable.
Keep in mind the choke heater constantly draws current even when it’s open. It’s also possible that there are other wiring issues that have caused low voltage to the coil and the electric choke just made it so low the ignition system can’t fire off the engine.

 

[Lou C]

PS:
on older OMCs there are a few quirks in the wiring system, one is that the sense circuit (this senses actual battery voltage so the voltage regulator can adjust accordingly) can develop high resistance which causes the alternator to over charge the battery, this is solved by disconnecting the sense wire at the alternator and taping it up in the harness. Then make up a jumper wire from the large B+ terminal on the alternator and the sense terminal. When I did this on mine the battery voltage when charging dropped from 15.5 V to 14.2V which is what it should be. I actually leaned this from ARCO electric which sells marine alternators and starters, it was stated in the instructions for the new alternator I installed.
Next, some will have a problem with low voltage in the igntion circuit and gauge wiring circuits. You can test this by pulling out the ignition switch and checking voltages at the various terminals. At the B terminal there should be battery voltage (red wire) any time the battery switch is on. At the I terminal (purple wire for ignition circuit) there should be battery voltage when you turn the ignition switch on. Same thing with the S terminal (s for start, yellow/red wire). On mine I had 12.6 V at the B terminal but for the I terminal with the key on, it would drop to 11.5 V. Same thing noted at the fuse box positive terminal. I tried adding a supplemental ground wire thinking it was bad grounds but same result. Then did the same thing with the positive side and that fixed it. So I wired in a supplemental power lead with an 8 gauge wire fused at the battery common stud. This, combined with a modern PMGR starter, turned this boat into a very good starting machine. The wiring fixes assured full voltage to the coil and the modern starter draws less current than the old direct drive units.
Your issues may be found partly here, or in how the Splitfire ignition system was replaced, how was it wired up? The stock OMC points igntion used a conventional coil and a resistance wire. What do you have in yours now?

 

[VIPUK]

Evening all - thanks for your info so far...

Spent all day on it today without sucess - but these are the things I learned:

• The spitfire ignition system has been replaced by something very similair to this https://repowermarine.com/index.php/delco-est-marine-ignition-system-for-4-3l-v6.html
• The spark is pretty weak but becomes almost non existent after about 10 minutes of runtime and the engine cuts out and is very relectnat to start, if oi starts at all...
• The alternatoir is kicking out 12v or therabouts (i'm sure it used to kick out 14v after a service at a local auto engineers, but the marine engineers insisted that wasn't correct and so presumably had the regualtor changed as it now produces 12v to the batteries?
• Even when 'hotwired' direct form the battery the problem persists - 10 minutes then it dies.
• If we connect up the Rev. counter it kills the engine - this didnt happen previously.....
• We've checked as many earths as possible and reconnected several that were left hanging...
• The digital voltage meter that was fitted as part of the refit is reading bhetween 11.8 and 12.2 - but does seem to drop a little as the engine dies...
• There doesnt seem to be any power to the choke..
• We have a twin battery set up - could this be relvant?

So, it feels to me like a faulty coil - what do you think?

 

[VIPUK]

@Lou C
"Next, some will have a problem with low voltage in the igntion circuit and gauge wiring circuits. You can test this by pulling out the ignition switch and checking voltages at the various terminals. At the B terminal there should be battery voltage (red wire) any time the battery switch is on. At the I terminal (purple wire for ignition circuit) there should be battery voltage when you turn the ignition switch on. Same thing with the S terminal (s for start, yellow/red wire). On mine I had 12.6 V at the B terminal but for the I terminal with the key on, it would drop to 11.5 V. Same thing noted at the fuse box positive terminal. I tried adding a supplemental ground wire thinking it was bad grounds but same result. Then did the same thing with the positive side and that fixed it. So I wired in a supplemental power lead with an 8 gauge wire fused at the battery common stud."

...will try this tomorrow too. Thanks

 

[Lou C]

Well you can simply measure the primary & secondary resistance of the coil against specs. Do it after running the engine as long as it can so it is hot you want to see if it breaks down when hot.
The “engineers” need to go back to “school” if they think a simple marine charging system charges the battery at 12v. It doesn’t! Normal charging voltage is about 14.2 V.
Show this to your “engineers” and ask for an explanation.

 

[VIPUK]

Well you can simply measure the primary & secondary resistance of the coil against specs. Do it after running the engine as long as it can so it is hot you want to see if it breaks down when hot.
The “engineers” need to go back to “school” if they think a simple marine charging system charges the battery at 12v. It doesn’t! Normal charging voltage is about 14.2 V.
Show this to your “engineers” and ask for an explanation.
View attachment 341479

Thanks - How would I go about measuring the primary and secondry resistance at the coil as you have suggested?

 

[Lou C]

You need a decent digital volt ohmmeter and the specs for the Delco EST system, it shouldn’t be hard to find because Volvo Penta used that same system for years. I don’t know off had because my OMC still has the original points system which works fine if you know how to maintain them.

 

[VIPUK]

You need a decent digital volt ohmmeter and the specs for the Delco EST system, it shouldn’t be hard to find because Volvo Penta used that same system for years. I don’t know off had because my OMC still has the original points system which works fine if you know how to maintain them.

Mine had a 'Spitfire' system on the old (pre vortec) engine.... the engineers said they needed to change to the distributor system as spitfire was obselete and wouldn't work with the vortec?

 

[Lou C]

That they are right about. No parts available only used a few years. Actually better off with the previous breaker point system, I still have it on mine.

 

[VIPUK]

So we've changed tack on this issue for the time being - the engineers, althought too busy to come and actually look at the boat, sent a text insisting its a fuel issie. so i checked all the fuel lines and the pump off the boat - all good. the issue seems to be the fuel pick up from the tank...

 

[VIPUK]

So now i need 2 of the (american) screw in to10mm push on fittings....
and a suggestion for a new fuel pick up......
and replacement fuel sender....
is there an emoji for crying on here?

 

[VIPUK]

Upadte on this - issue appears to be resolved!

Afer replacing the fuel pick up and all the fuel pipes the issue persisted - so after some more reasearch decided the issue could be vapour locking of the last section of the fuel delivery lines caused by a combiantion of heat build up and an incorrectly located fuel pump.

After relocating the fuel pump to before the fuel filter cartridge instead of after the issue seems to be resolved.

In addition to this i discovered that the wires to the choke on the carb were not live, so also wired in an ignition live.
Seems to run sweet and now plan to try her out in the water this weekend...
T
hanks for everyone's input!