Engine Stall under load/planing. 86 7.4’s
08-18-2024 | 09:22 PM
#1
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Engine Stall under load/planing. 86 7.4’s
Hi All,
I was out over the weekend all was well, cruising down the lake around 40ish mph and port motor started to stall and cut out. Stopped and did a quick check, restarted a little hard idled a few seconds and cut off. After a bit of this process idled out a little rough, would rev ok in neutral, start to plane and about 2000-2500 would cut out and repeat. If I backed off throttle quick enough would save it, otherwise stall out. Limped it to docks near me, changed fuel filter as I had just got gas, didn’t help. Eventually got on plane, cruised 5 minutes back to my actual slip and same thing, was running on plane died out, and same process. Was like it had to build back up slowly then would plane ok, still not 100% power wise it seemed when running or dropping into gear. 1986 Scarab, stock 7.4’s, thunderbolt vi ignition. Didn’t have time to check much, started thinking fuel, but starboard still running fine. Any initial checkpoints? TB system? Haven’t changed anything ignition wise since I’ve had it since 2018, but first issue engine related…
Thanks!
I was out over the weekend all was well, cruising down the lake around 40ish mph and port motor started to stall and cut out. Stopped and did a quick check, restarted a little hard idled a few seconds and cut off. After a bit of this process idled out a little rough, would rev ok in neutral, start to plane and about 2000-2500 would cut out and repeat. If I backed off throttle quick enough would save it, otherwise stall out. Limped it to docks near me, changed fuel filter as I had just got gas, didn’t help. Eventually got on plane, cruised 5 minutes back to my actual slip and same thing, was running on plane died out, and same process. Was like it had to build back up slowly then would plane ok, still not 100% power wise it seemed when running or dropping into gear. 1986 Scarab, stock 7.4’s, thunderbolt vi ignition. Didn’t have time to check much, started thinking fuel, but starboard still running fine. Any initial checkpoints? TB system? Haven’t changed anything ignition wise since I’ve had it since 2018, but first issue engine related…
Thanks!
Last edited by Dboss33; 08-19-2024 at 07:28 AM.
08-18-2024 | 10:13 PM
#2
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Joined: Jun 2011
Posts: 1,208
Likes: 141
Hi All,
I was out over the weekend all was well, cruising down the lake around 40ish mph and port motor started to stall and cut out. Stopped and did a quick check, restarted a little hard idled a few seconds and cut off. After a bit of this process idled out a little rough, would rev ok in neutral, start to plane and about 2000-2500 would cut out and repeat. If I backed off throttle quick enough would save it, otherwise stall out. Limped it to docks near me, changed fuel filter as I had just gotten gas, didn’t help. Eventually got on plane, cruised 5 minutes back to my actual slip and same thing, was running on plane died out, and same process. Was like it had to build back up slowly then would plane ok, still not 100% power wise it seemed when running or dropping into gear. 1986 Scarab, stock 7.4’s, thunderbolt vi ignition. Didn’t have time to check much, started thinking fuel, but starboard still running fine. Any initial checkpoints? TB system? Haven’t changed anything ignition wise since I’ve had it since 2018, but first issue engine related…
Thanks!
I was out over the weekend all was well, cruising down the lake around 40ish mph and port motor started to stall and cut out. Stopped and did a quick check, restarted a little hard idled a few seconds and cut off. After a bit of this process idled out a little rough, would rev ok in neutral, start to plane and about 2000-2500 would cut out and repeat. If I backed off throttle quick enough would save it, otherwise stall out. Limped it to docks near me, changed fuel filter as I had just gotten gas, didn’t help. Eventually got on plane, cruised 5 minutes back to my actual slip and same thing, was running on plane died out, and same process. Was like it had to build back up slowly then would plane ok, still not 100% power wise it seemed when running or dropping into gear. 1986 Scarab, stock 7.4’s, thunderbolt vi ignition. Didn’t have time to check much, started thinking fuel, but starboard still running fine. Any initial checkpoints? TB system? Haven’t changed anything ignition wise since I’ve had it since 2018, but first issue engine related…
Thanks!
08-29-2024 | 09:05 PM
#4
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Joined: Apr 2014
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Well… Progress maybe, was able to get to it today and replaced rotor, dist. cap, coil, and ignition sensor. Ran beautiful for 10 minutes and stopped on purpose, upon trying to replane it didn’t stall like before but had a noticeable miss and struggled to plane, and could feel a miss while driving. Tach seemed to be jumping around a few hundred rpm’s too passed idle speeds which I haven’t seen before.
Will try plugs and wires next. Would think the struggles under load once the engine bay is hot would not be fuel related? Most of the parts I replaced had to be stock or at least 20 years old by the looks of them.
Thanks!
Will try plugs and wires next. Would think the struggles under load once the engine bay is hot would not be fuel related? Most of the parts I replaced had to be stock or at least 20 years old by the looks of them.
Thanks!
