No power under load


Many thanks for this. It is much appreciated.

I will check the siphon valve and the pickup tube.

I think I have tried Bundaberg Rum once, but only once. Glad you like. We actually live in a rural area just outside Bundaberg where the rum is made. Did not realise Bundaberg Rum was sold in the US.

I will check the VST and the pressure in the fuel rail and try that DIY LED scanner.

Got to go away for a week. So will take a little while before I have investigated each possibility.

We really want that boat to work. We have another boat, a 1988 Malibu Skier, but I really like the Formula. Of course, they are a different class of boat. But the Formula is nicer than the Malibu to drive - cuts through wake with no problems and a lot roomier - and probably actually easier to get off and on the trailer even though quite a lot bigger.
 
I did have some time today (our trip away was delayed) and I removed the fitting that is supposed to have the anti-siphon valve in it and there was nothing in it. Some body has evidently already removed it - I am the third owner.

Could not budge the pick up tube. Got a socket around it but could not budge it. Would obviously have to use a considerable amount of force.
 
So it was just a fitting? No ball/spring check valve? I would listen to Alldodge. That could be costly if you ever had a leak.
 
Thanks for that. Yes, just a fitting, nothing inside it. I will replace it.

Had time today to check for codes with the DIY scan tool - 12V LED and paper clip. No codes are stored. I just got the 12 code repeatedly and nothing else.

So what does that mean? Shall I continue and remove the plenum and check the schraeder valve on the fuel lines? Does this have to be done while the engine is running?
 
Just removed the ignition coil and tested it with a multimeter according to the instructions in this document:

[h=3]PDF]Delco EST Ignition System[/h]
and my coil appears to fail every test.

It is difficult to get a good contact with the probes on the multimeter, but I did try a number of times and I got infinite resistance for every test.
 
While the coil may be causing some performance issues, I don't see it as being the current problem. Getting infinite readings on every test means your not getting contact, because if this was the case the motor wouldn't run at all. Would need to find a small piece of wire to insert into the plug.

The pressure is read while the motor is running, and it needs to be able to read up to 60 psi or more. It screws onto the shrader valve. Don't remove the plenum, it is tight but it can be connected. There is a cover cap over the valve that needs to be removed. The valve is above the fuel pressure regulator
 
You were right about the coil. I rechecked it with some paper clips inserted into the plug and the resistance readings are about normal.

I am away from home at the moment and could be away fro about a week and the boat is at home. What sort of fuel pressure gauge do I need to connect to the schrader valve? Just the sort that you can get from an automotive parts shop?
 
Have returned from our week away. Bought a fuel injection pressure tester on eBay.

Is the schrader valve located at the front of the motor on the LHS just below what I think is the fuel regulator? If so, I have not been able to get a fitting onto it. I have right angled fittings and they are very difficult to attach. Either I will have to remove the plenum or find some straight fittings.
 
The Shrader valve is directly behind the thermostat housing. The rubber line in the pic goes to the regulator and the valve is above it. I would not remove the plenum, this will break the gasket seal and then they will need to be replaced.

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Many thanks for that help. Yes, I see it now, just above the fuel regulator and I have managed to screw a fitting onto it and connect to the fuel pressure gauge. It was tight but just possible.

What do I do now? Run the engine at idle and higher rpm? What should I observe regarding fuel pressure?

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Sorry that last picture is upside down. But you should still be able to see the hose connected to the Schrader valve above (or below in the picture since it is upside down) the regulator.
 
Turn key ON and watch the gauge, note the pressure and how long it stays there. You can turn the turn OFF and back ON a couple times to see how it reacts/changes. Start the motor and note pressure, then take it for spin and keep track of the pressure and at what throttle
 
I turned the key to ON and the fuel pressure gauge did not move. I am fairly sure it was in the ON position - a green light comes on and the dash fuel gauge and voltmeter respond and the key switch is obviously spring loaded beyond that point. Thought also that I should hear the fuel pump running, but I do not.

When you turn the key off you do hear some noise like a momentary light 'clicking'. That noise might be there when you turn to ON also, but another noise also sounds in that position so I cannot distinctly hear anything else.

But should the noise of the high pressure fuel pump be more distinct than that (like on a car where you can hear the pump running while the ignition is on), so that while the key is in the ON position you should be able to hear the whirring of the high pressure pump?
 
Yes, you should hear the pump run for 2 to 3 seconds when key is turned ON. If the pump didn't run there will be no pressure and the motor won't start. There is two relays inside the box on the port side. One is main power and the other is the fuel pump. Both are the same relays and can be swapped with each other, and are also fuse protected. Fuses are covered with rubber boots
 
I just went up to the boat shed to check. Schrader valve does not appear to be leaking fuel, but it also looks like the fitting onto it could be tightened a few more turns. But it is very difficult to get your fingers in there to tighten it. Will have another look in the morning to see if I can get some pin nose pliers in there to help me tighten it up - its half past midnight here now.

When you turn to ON you can hear two clicks but about 2-3 seconds apart. And when you turn to off, you hear about 5 clicks in quick succession. Might pull the boat out of the shed and start it on the hose in the first instance. It never usually has any trouble starting. Anyway, once it has started, you would know straight away whether the fitting to the Schrader valve was properly connected I suppose, because if it still read zero on the gauge with the engine running there must be a problem with the fitting.

Many thanks again. Will let you know how I get on. But might have to wait till Saturday to pull the boat out and get my wife to give me a hand.
 
Finally got that fitting onto the Schrader valve so that it seems to be tight. We pulled the boat out of the shed on Saturday and hooked up the hose and found some interesting things. Engine started on the second turn of the key. You have to recall that I did have the fuel line disconnected from the tank to check that ball valve in the fitting at the tank, so naturally the manual pump would have to pump fuel in that line again after the hose had been reconnected. At first, I thought the fuel pressure gauge was not working, or that the fitting was not secure on the Schrader valve, but having confirmed that there was no leak I then noticed that the gauge was reading 10 psi and slowly climbing. It climbed up to 30 psi at idle (750 rpm). I opened the throttle to about 1800 rpm and it was about 28 psi, at 2500 rpm it was 27 psi. I then turned the engine off and it went back to 30 psi. (It would remain at that pressure for quite awhile and only slowly drop down if you left it for quite a few hours.) If I then turned the ignition to ON it would read 34 psi. If I then started the engine it would drop back down to read 30 psi at idle (750 rpm).

I am wondering if there is a high pressure fuel pump problem because from my checking on the internet a 454 Magnum MPI in a 1997 boat should show about 42 psi. Would that be correct? Also, the slight drop in fuel pressure with the increase in rpms even while not under the load of actually pushing the boat through the water makes you wonder what the psi is when it is under load pushing the boat along above about 3000 rpm.

Anyway, I connected a multimeter this morning (Monday) to where the wires connect to the high pressure fuel pump and turned the ignition to ON. The meter momentarily (for about a second - about the same amount of time a high pitched noise at the instrument panel can be heard) reads about 11.6V and then drops to zero. If you then turn the ignition OFF and then back ON again it does the same thing. It would seem that the high pressure fuel pump is coming on momentarily and then the relay turns it off(?). If you keep doing this, turning to ON then OFF, you can notice the fuel pressure rise by increments of about 2 psi each time, until eventually you get back up to about 34 psi (without firing the engine).

What would stop the high pressure pump from continuing to pump so that the pressure got up to 34 psi in one go (if 34 psi is indeed all it is supposed to raise the pressure to)?

I did also swap the two relays in the black box but I cannot confirm that the voltage reading was the same (because the battery in the multimeter was about to give out), but there was no change in the pressure reading when the ignition was turned ON. I did also check the earth for the fuel pump which I am told is at the bell housing to see if it looks ok. Did not look great but I did not take it apart to check more thoroughly to see that it was making a good connection, though a check with the multimeter indicates that it is ok - about zero ohms resistance between the negative terminal on the pump and the bellhousing bolt itself, not just the wire attached to it.

The pictures below give some illustration of what I have done:

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