1988 GM 5.7 stalling when slowing down

[Boater1999]

Hello ! I have a 1988 Rampage 24 Express with a GM 5.7 L and a Quadrajet 4 barrel. I recently replaced the thunderbolt IV ignition with a Sierra Marine Delco EST Distributor. Had a problem with the first 2 do to it cutting out between 2300-3000 rpm . This one ( the 3rd ) I can get it to power up without it cutting out but now when I pull the throttle back form cruising speed (3100 rpm ) the engine dies like I just turned the key off . Starts back up but once back up to 3100 rpm and back off the power it dies again . slowly going out of my mind . Any help would be appreciated.

 

[Rick Stephens]

Might have someone retard the throttle for you while you look at the shift interrupt switch and see if it is activating when you retard the throttles. Have seen that with a maladjusted set of cables/linkages.

 

[Boater1999]

Might have someone retard the throttle for you while you look at the shift interrupt switch and see if it is activating when you retard the throttles. Have seen that with a maladjusted set of cables/linkages.

Would it doit if the boat I not in gear ?

 

[Eric 3.7LX Alpha 1]

The shift interrupter switch is only suppose to engage when shifting from either F or R into neutral.... and only in the water. Water adds load on the prop that you don't get on a trailer.

 

[hgxsilver]

How does it start up? Does it start differently after you've had it running ? Im thinking fuel problem

 

[kenny nunez]

If everything else is not causing the problem what you are describing then it could be possible the rotor gets hot in the distributor and is going to ground. When the boat is coming off of plane it loads the ignition more than when it is on plane.
Get an extra rotor and see if that helps.

 

[tank1949]

The shift interrupter switch is only suppose to engage when shifting from either F or R into neutral.... and only in the water. Water adds load on the prop that you don't get on a trailer.

Suppose to, but switch may be closing intermittently. It is my understanding that all adjustment and tests should be performed while boat is in water. I had an Alpha that drove me nuts. A shop and I could never get it to reliably work. I am guessing that slop in the linkage cause the issue, but the shop indicated that it wasn't. I sold boat along with headaches. .

 

[crazy charlie]

I had similar many years ago.Check the Quadrajet filter.Make sure you have a marine filter and not an automotive filter.A car filter is designed to cut off fuel if the vehicle is on its side or worse.Coming on or off plane may trigger same.You will need a slim carb wrench to get the filter out. It will be good to change this filter anyway.Charlie

 

[tank1949]

I had similar many years ago.Check the Quadrajet filter.Make sure you have a marine filter and not an automotive filter.A car filter is designed to cut off fuel if the vehicle is on its side or worse.Coming on or off plane may trigger same.You will need a slim carb wrench to get the filter out. It will be good to change this filter anyway.Charlie

and filter inside quad/line. Not normally on a marine engine, but someone may have added one.

 

[Boater1999]

Thank you all for the help . I checked the interrupter switch and it doesn’t move at all when pulling the throttle back . This problem happens when coming off of plane and at the slip when I’m running just the throttle not putting it in forward or reverse . I will check the other mentioned stuff this weekend when I have more time and update thanks again to all of you .

 

[Cdn20valve]

Hello ! I have a 1988 Rampage 24 Express with a GM 5.7 L and a Quadrajet 4 barrel. I recently replaced the thunderbolt IV ignition with a Sierra Marine Delco EST Distributor. Had a problem with the first 2 do to it cutting out between 2300-3000 rpm . This one ( the 3rd ) I can get it to power up without it cutting out but now when I pull the throttle back form cruising speed (3100 rpm ) the engine dies like I just turned the key off . Starts back up but once back up to 3100 rpm and back off the power it dies again . slowly going out of my mind . Any help would be appreciated.

Check for water in fuel. I hat this problem before. When slowing down, due to angle of the boat, the fuel pickup would suck up water and stall at idle. Check water seperator for water.

 

[Boater1999]

So I bought a inline spark tester connected to to the #1 plug wire and fired up the engine and ran it up to 3200 rpm’s ( in Neutral at the dock not in forward or reverse. ) spark quit for a brief second around 2200 rpm’s then continued to fire up to 3200 rpm’s as soon as I started to pull the throttle back to idle I lost all spark ( just like I had turned the key to the off position) getting very frustrated. Not a fuel or air problem it’s getting plenty . Anyone have any suggestions? I’m thinking coil or ignition control module

 

[kenny nunez]

Get a volt meter and connect it to the + side of the coil and perform the same test.

 

[Boater1999]

Get a volt meter and connect it to the + side of the coil and perform the same test.

With this being an aftermarket coil and distributor what should the ohms be in between On the coil ?

 

[kenny nunez]

Did you purchase the Sierra# 18-5514 kit? It came with the correct coil.
The ohm readings are on the internet.

 

[nola mike]

So I bought a inline spark tester connected to to the #1 plug wire and fired up the engine and ran it up to 3200 rpm’s ( in Neutral at the dock not in forward or reverse. ) spark quit for a brief second around 2200 rpm’s then continued to fire up to 3200 rpm’s as soon as I started to pull the throttle back to idle I lost all spark ( just like I had turned the key to the off position) getting very frustrated. Not a fuel or air problem it’s getting plenty . Anyone have any suggestions? I’m thinking coil or ignition control module

Moving the throttle back/cutting spark, wondering if you're somehow triggering your MOB switch. I'd suspect an intermittent connection problem somewhere over a bad coil/module

 

[Boater1999]

Yes I got the same Sierra part number as mentioned above . I do not have a MOB switch on this boat . But what I did last night was bypass the neutral safety switch to see if that may be getting triggered when I pull the throttle back and it still dies. I also put the inline spark tester from the coil to the top of the distributor and I loose all power to the coil when pulling the throttle back . Let’s just say it’s running rich and the engine has to much unburned fuel when pulling back which may or may not be the problem , I would think I would still get constant 12 volts to the coil until the engine comes to a complete stop with the key still on wouldn’t I ? Is there something between the key and coil that might be bad ? Would there be a crank sensor on a engine this old ? Would it be worth a try to disconnect the 12v coming from the key and run a 12v jumper wire directly from the battery to the coil ? Thanks in advance for what everyone has suggested thus far

 

[nola mike]

Yes I got the same Sierra part number as mentioned above . I do not have a MOB switch on this boat . But what I did last night was bypass the neutral safety switch to see if that may be getting triggered when I pull the throttle back and it still dies.

Neutral safety affects the starting circuit only

loose all power to the coil when pulling the throttle back . Let’s just say it’s running rich and the engine has to much unburned fuel when pulling back which may or may not be the problem , I would think I would still get constant 12 volts to the coil until the engine comes to a complete stop with the key still on wouldn’t I ?

Yes, clearly electrical problem

Is there something between the key and coil that might be bad ? Would there be a crank sensor on a engine this old ? Would it be worth a try to disconnect the 12v coming from the key and run a 12v jumper wire directly from the battery to the coil ? Thanks in advance for what everyone has suggested thus far

Yes/no/yes, but you won't be able to shut the engine with the key.

All the wiring between the battery, through the engine harness cannon connector, up to the ignition switch (red/purple wire), through the fuses, through the ignition switch and back. All need to be checked. Did you check for voltage at the coil pos when you lose spark?

 

[achris]

It's only doing it when you move the throttle, so it's something to do with that.

Now that you have isolated the problem down this far (and really well done on getting this far so quickly ) It should be a fairly 'easy' matter to track it down to the source.

I would get a 12 test light (something very simple like a 12v festoon with wires and a croc clip on each end) and connect it to the coil + terminal. This should have 12v on it any time the key is ON. Turn the key ON (engine not running) and see that the light is on. Now move the throttle and see if you can make the light go out. When it does, see what's touching anything new. (You may have a simple abraded wire that's being shorted to ground by the throttle cable.)

Chris..........

 

[Boater1999]

Neutral safety affects the starting circuit only


Yes, clearly electrical problem



Yes/no/yes, but you won't be able to shut the engine with the key.

All the wiring between the battery, through the engine harness cannon connector, up to the ignition switch (red/purple wire), through the fuses, through the ignition switch and back. All need to be checked. Did you check for voltage at the coil pos when you lose spark?

Neutral safety affects the starting circuit only


Yes, clearly electrical problem



Yes/no/yes, but you won't be able to shut the engine with the key.

All the wiring between the battery, through the engine harness cannon connector, up to the ignition switch (red/purple wire), through the fuses, through the ignition switch and back. All need to be checked. Did you check for voltage at the coil pos when you lose spark?

No I did not check for voltage I only put the inline spark tester on to see if I have power to it . I will try that this weekend .