Mercury EFI 150 SURGE

[darrall]

1996 S/N OG422879
Only time I have really noticed it is at take off.
Usually within the first 100 yards. Quick RPM drop & then jumps back up. Almost like it doesn't have fuel for a second. Very noticeable jerk.
From 1 to 3 times quickly when it does it. Sometimes it doesn't do it at all.
After it does it once it doesn't seem to do it again unless I stop and fish then take off again.
Doesn't seem to matter if I change tanks, still does it.
Changed the plugs & also rebuilt the pulse pump with no change.
Water separator is clean. Idle is good. Fires right up.

Thanks,
Darrall

[leonreno]

But could also be fuel pump (use fuel pressure gauge to check) or maybe reeds, maybe just needs the timing checked, tps sensor adjusted ore replaced. Also might consider removing idle stabalizer, could cause such problems.

[JOE54]

^^^+1 need fuel psi reading for sure when it surges

[darrall]

Is there a video out there anywhere that shows how to do the PSI reading?

[JOE54]

probly, if you had a gage you could just observ pressure when surges and report back

[darrall]

Is there already a port on the motor to connect the gage too?
What should the readings be?
Thanks

[leonreno]

Should be a schrader valve connection. Not sure where myself but someone should know that and the correct pressure. If you search this forum you probably can find the answer also.

[JOE54]

look on top of vst in brass fitting, 39 lbs +- 1 or 2

[EuropeanAM]

Depending on your gauge, it may indicate 34-36 psi. Need to know what you are getting on YOUR engine, and also monitor it while the engine is doing what you are concerned about.

SAFETY FIRST- anything above idle will require you have someone VIDEO the gauge readings while you run the boat.

[darrall]

Depending on your gauge, it may indicate 34-36 psi. Need to know what you are getting on YOUR engine, and also monitor it while the engine is doing what you are concerned about.

SAFETY FIRST- anything above idle will require you have someone VIDEO the gauge readings while you run the boat.

25 PSI. Gage pretty much never moved, even the couple times it did the surge.

[JOE54]

check all harness and wire connectors /connections

[darrall]

check all harness and wire connectors /connections

Could have told me to do that last week...LOL

[JOE54]

process of elimination

[darrall]

process of elimination

So the 25 PSI that's supposed to be 35 doesn't lean towards fuel pump?
Pulse pump has been rebuilt with new guts.
I'm just trying to do as much as I can when I'm with the boat.
It stays at our place at the lake & weekends is my only chance to try what could be suspect.
Thanks!

[JOE54]

you trust that gage is absoultely correct ,if so psi is tooooo low

[jtipton91]

Ecu id bet

[darrall]

you trust that gage is absoultely correct ,if so psi is tooooo low

Well it was brand new out of the box. So I hope so. I'll check it.

[EuropeanAM]

I agree- 25 psi is way too low (going to be a very unhappy engine). But... verify the gauge's accuracy before jumping to conclusions.

[darrall]

I agree- 25 psi is way too low (going to be a very unhappy engine). But... verify the gauge's accuracy before jumping to conclusions.

Just tested the gage & it is accurate.

[JOE54]

procede to pump screen inspection and or pump replace must achieve 36-39 psi