acceleration cuts out briefly

Rjsnyc

Rjsnyc

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I have an M30B35 engine (fuel injected) in my 1973 CS. I've owned it for six months now, so ironing out some kinks. Last week, occasionally when I hit the pedal hard the gas cuts out for a second or two. This at causing speed or at least while engine is warm. When I let off it kicks back in. Sure this could be a number of things. Are their know culprits? Or where I could look to start? (there is a gas smell in the cabin, which I put in another post, but doubt they are related.)


Thanks in advance. Randy
 
Rjsnyc said:
The pump has been noisy. I’ll check it. Should it be somewhat quiet? Can definitely hear it from the cabin.
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you can usually hear it prior to engine firing.I was getting the ocasional intermittent"stutter"at highway speed and had my suspicions but it finally chose to stop on a very hot day at a major intersection ( peak hour!) . Once it cooled down it atarted working again but I replaced it for obvious reasons.
 
It cuts out under hard acceleration but only has power again if you back off the throttle? If you keep it under hard acceleration it never recovers? Also, is it a crisp cut out of power or does it stumble at all? Ignition versus fuel.
 
dang said:
It cuts out under hard acceleration but only has power again if you back off the throttle? If you keep it under hard acceleration it never recovers? Also, is it a crisp cut out of power or does it stumble at all? Ignition versus fuel.
Click to expand...

It cuts out under hard acceleration but only has power again if you back off the throttle? - yes

Scenario. Traffic light turns green. First gear then second. Second to third, have some fun, gun it to 4k rpm. Fuel Blips out. I Back off. Back to normal.

If you keep it under hard acceleration it never recovers? - It feels like it Could die if I stay on the gas. So I back off. Haven’t pushed it further. I’m generally in traffic. immediate fear was shi* I’m going to stall.

Also, is it a crisp cut out of power or does it stumble at all? - As I remember,
it is crisp.

Btw, I'm aware of all the concentration you all are spending here and it's greatly appreciated.
 
Last edited:
Found the Fuel pump is brand new. Only has couple a couple hundred miles on it. Previous owner. A timing issue?
 
You can rent a fuel pressure tester at a parts store. The kit has a T-fitting you plumb into the supply hose at the back of the fuel rail (assuming log manifold, on the B35 manifold they run supply and return at the bottom of the plenum in the middle). You're looking for 40-45psi of fuel pressure. To test this under load, you'll have to hook up the tester and tape the gauge to the windshield, carefully routing the hose so it's not pinched by the hood and when it cuts out you can see where the fuel pressure is. If it doesn't change, it's not a fuel delivery issue.
 
Remove the fuel filter and drain it backwards into a glass jar and see what comes out
 
Are you still in touch with the previous owner? You say it has a new fuel pump/filter from the previous owner so it sounds like they may have been chasing the issue also. Could be more complicated than just a fuel filter. Injection stuff isn't my forte.
 
Thx to the last five of you. Last owner said there was no fuel issue, but why would he change the pump? Suggested timing. Regardless, I’ll take all that you’ve said in mind. Thank you.
 
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