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Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Thu Aug 06, 2020 4:35 pm
by AsLan7
rabiddawg wrote: Thu Aug 06, 2020 4:17 pm

1. The tester is showing 45 psi on the rail key on pump on. When pump quits it drops to 40 and holds. It’s been there for 30 minutes now. At idle and if I rev it it holds at 40 psi. These numbers seem good based on what I have been able to find.


2. Cranked again on hose. Pressures at the rail were the same at key on and idle.

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Did you pump any fresh fuel into the tank yet after draining?

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Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Thu Aug 06, 2020 5:51 pm
by rabiddawg
Yes I added 5 gallons of nonE to run it I. My parking lot. I will ad more when I drop it in a lake.

Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Thu Aug 06, 2020 5:57 pm
by AsLan7
rabiddawg wrote: Thu Aug 06, 2020 5:51 pm Yes I added 5 gallons of nonE to run it I. My parking lot. I will ad more when I drop it in a lake.
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Roger that rd. Looking forward to your Captain’s report. 👍🏻

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Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Thu Aug 06, 2020 6:42 pm
by Big Block Power
Watch this vid
Low pressure and high pressure testing.


Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Thu Aug 06, 2020 7:13 pm
by AsLan7
Big Block Power wrote: Thu Aug 06, 2020 6:42 pm Watch this vid
Low pressure and high pressure testing.

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Hmmm. What am I missing with the fuel pressure posts?
I’m not seeing any issues with his low and high pressure fuel pumps based on rabiddawg’s verbiage.
LPFP= 0psi when key turned on and 12psi with engine running. Pass
HPFP= 45psi when key turned on and 45psi with engine running. Holding 40psi after shut down. Slightly low holding but a Pass in my book.
Enlighten me brutha bbp. 🤔

I’m thinking phase separated gas is the issue.

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Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Thu Aug 06, 2020 7:15 pm
by Big Block Power
AsLan7 wrote: Thu Aug 06, 2020 7:13 pm
Big Block Power wrote: Thu Aug 06, 2020 6:42 pm Watch this vid
Low pressure and high pressure testing.

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Hmmm. What am I missing with the fuel pressure posts?
I’m not seeing any issues with his low and high pressure fuel pumps based on rabiddawg’s verbiage.
LPFP= 0psi when key turned on and 12psi with engine running. Pass
HPFP= 45psi when key turned on and 45psi with engine running. Holding 40psi after shut down. Slightly low holding but a Pass in my book.
Enlighten me brutha bbp. 🤔

I’m thinking phase separated gas is the issue.

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From this. Key on no pressure.

Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Thu Aug 06, 2020 7:17 pm
by AsLan7
That’s normal with the key on and engine not running, no?
The video u posted shows the same. 0 with key on. 10 while running.
I’m not seeing any fuel pump issues. Never hurts to check the screen of course.

Hopefully the fresh gas Captain’s run report will be telling. 👌

Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Thu Aug 06, 2020 7:30 pm
by Big Block Power
AsLan7 wrote: Thu Aug 06, 2020 7:17 pm That’s normal with the key on and engine not running, no?
The video u posted shows the same. 0 with key on. 10 while running.
I guess why have a 2 second prime if you don't get pressure? Maybe I'm wrong. Also in the vid hp should be 50psi. I didn't look at what the range is though. Just posting to help all. They are good vids.

Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Thu Aug 06, 2020 7:39 pm
by AsLan7
Big Block Power wrote: Thu Aug 06, 2020 7:30 pm
AsLan7 wrote: Thu Aug 06, 2020 7:17 pm That’s normal with the key on and engine not running, no?
The video u posted shows the same. 0 with key on. 10 while running.
I guess why have a 2 second prime if you don't get pressure? Maybe I'm wrong. Also in the vid hp should be 50psi. I didn't look at what the range is though. Just posting to help all. They are good vids.
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RD’s HPFP rail pressure is slightly low (5 psi below 50 in your vid) which could be some paint flecks in the screen. Nothing too abnormal though. LPFP 12psi. That’s fine.
That guy in the garage mechanic vid is going to blow himself up. No blower on for 2-4 minutes...fuel dripping...tester hanging next to running serpentine belt :roll: Good Lord.

In any event, starting with fresh fuel and filters knowing fuel pressure is within limits should help to diagnose.

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Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Fri Aug 07, 2020 5:03 am
by rabiddawg
I read somewhere on the net that the 8.1 high pressure spec was lower than the smaller engines? Based on what I read mine is ok but I could be wrong. It’s frustrating trying to find the info. So many boat threads just stop with no resolution.

I’m hoping the low pressure pump wire was not connected properly. It definitely was not powering up at first. After I hot wired it to see if it would run and checking the plug for voltage (12v) It started working.

I removed the regulator. On mine the screen is down in the housing not on the regulator. It looked clean

I hope to water test it later today.

Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Fri Aug 07, 2020 5:21 am
by rabiddawg
This is from a thread on hull truth

I think I may have fuel pump issues, and would welcome any input. According to the Seloc manual, my pump should be at 36-44 lbs. at idle.

Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Fri Aug 07, 2020 6:04 am
by Big Block Power
Yes you are correct. I was incorrect on tyne bb spec. The sm pressures are 50. The bb spec you have is correct. Sorry for the confusion of was my sons fault not mine. Yes I agree so many threads just dead end. One of my frustrations as well. I told A7 this a bit ago. We try to help as much as we can then you never hear back from the poster. Gets very frustrating on our end but that's forums I guess.

Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Fri Aug 07, 2020 7:42 am
by AsLan7
Ya. It’s the nature of forums. Folks get on the train and off the train at different stops. Don’t take it personally.
I think the majority of CChat threads show some type of resolution. I definitely know they show some type of derailment. :lol: :lol:

Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Fri Aug 07, 2020 9:49 am
by rabiddawg
😂

Re: 8.1 Gi-c sluggish hole shot and sputter at wot

Posted: Fri Aug 07, 2020 2:25 pm
by rabiddawg
Water test sndcit still ran like crap.

I’m going to check the low pump again. I’m betting it’s not running again. Thinking the connector is bad.

Now the engine hatch won’t open 🤬

And the walk thru door broke where the latch is screwed to it. Damn rough La. roads