Power loss VP 5.7 Gi-D (with Video)

dacarter

Petty Officer 2nd Class
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Mar 6, 2013
Messages
106
Re: Power loss VP 5.7 Gi-D (with Video)

The dip stick tube fitting screws into the stock GM drain plug threads, so the pans are identical, but items that attached to the pan are not.

Definately aware that some parts are special for safety reasons and should not be substituted.
 
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dacarter

Petty Officer 2nd Class
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Mar 6, 2013
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Re: Power loss VP 5.7 Gi-D (with Video)

Now I'm really confused... I did some more research on the auto vs marine distributor caps and found this writeup on NAPAs site where they claim their aluminum contacts will corrode less than brass. NAPA specifically markets this cap for VP 5.7. It is not vented, which sounds good for a marine cap, but doesn't have any type of gasket or seal where it meets the distributor.

http://www.napaechlin.com/upload/NAPAEchlin/Documents/English%20PDFs/DYK_Improved_GM_cap.pdf
 

MikDee

Banned
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Jun 6, 2007
Messages
4,745
Re: Power loss VP 5.7 Gi-D (with Video)

Well, That blows me away as well :confused: Accel, Blue Streak, Niehoff, and other high perf caps all have a better plastic, & either brass, or copper terminals? Thanks, good to know.
 

dypcdiver

Lieutenant Junior Grade
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Nov 1, 2005
Messages
1,039
Re: Power loss VP 5.7 Gi-D (with Video)

OK here is my cap after 6 months of storage, and it has the brass terminals too.
 

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dacarter

Petty Officer 2nd Class
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Mar 6, 2013
Messages
106
Re: Power loss VP 5.7 Gi-D (with Video)

Wow, looks like it really is a yearly maintenance item. I had my last boat with a Merc 5.0, 2000 model, for 11 years and I don't think I ever changed the cap. The boat always ran perfect.
 

Walt T

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Mar 16, 2002
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1,369
Re: Power loss VP 5.7 Gi-D (with Video)

The voltage hopping from the rotor to the cap is pretty substantial and it'll jump better than Evel Knievel over a line of dancing ladies with Marge Simpson type hair. Both those pictures of caps arent that bad in my opinion but I don't let mine get that bad so I don't see that too much. I suggest keeping a spare cap, rotor, and plugs on the boat along with tools to change them. Can save a weekend.

The anti siphon is to prevent fuel from draining out of the line and back into the tank thereby causing a hard starting situation. It's not about safety, most if not all mechanical pumps had them. However if the carburetor has gas still in the bowl it will start right up and supposedly the pump will reprime in time before the bowl runs dry. The siphon valve also helps the fuel diaphragm stay wet with gas and therefore lubricated for a longer life. I have no problem leaving it out, but just bear it in mind if you seem to have first time of day hard start. Most distributors for marine use are designed to keep spark away from the outide of the cap. Sometimes that consiste of simply a O type gasket under the cap. Don't use automotive distributors. If there is a fire and someone is hurt or killed whether you planned it that way or not, once a lawyer knows about it he/she will bite onto that like a pit bull on a careless boaters gonads and never let go until your insurance company cries 'Uncle' and pays up. if you don't have insurance and don't own anything besides a waterlogged corroded up boat well then they can't get anything out of you except maybe your gonads which many a lawyer has on their walls signifying that they may not get blood out of a stone but they'll get gonads out of a bonehead.
 

dacarter

Petty Officer 2nd Class
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Mar 6, 2013
Messages
106
Re: Power loss VP 5.7 Gi-D (with Video)

Walt,

You are the first I have seen that said the Anti siphon is not about safety, but your reasoning makes some sense. I'll keep an eye out for hard starting on my MPI engine.

Anti Siphon Valves - BoatingHowTo.com

I do have some concern about the sealing of the cap since I was actually able to hear the arching (see video) when the engine was under load.
 

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
Re: Power loss VP 5.7 Gi-D (with Video)

Back in the day our my youth we would take a screw driver and place it in the cap between the center node and the outer plug nodes...If its a bad cap you should see the spark jump all over the place...the spark will find the any crack's or bad node's.
 

Walt T

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Mar 16, 2002
Messages
1,369
Re: Power loss VP 5.7 Gi-D (with Video)

Sounds like I'm wrong about the anti siphon valve, but automotive mechanical pumps have em too. They're integral and part of the inlet outlet valves. That article doesn't quite make sense. It only works as a safety valve if the fuel tank is above the carburetor or if the fuel line dips below the tank level. Here is something from USCG...

http://www.uscgboating.org/assets/pdf/_GIFS_FUEL/FUEL-F34.gif

It's pretty neat how I never stop learning coming here. All these years I thought I knew antisiphon valves. More to em than I thought. That's what I like about this joint I rolled it nice and packed uh wait I mean this joint meaning this forum isn't about who's right or who's wrong it's about sharing information. Ya'll can forget about that joint info tho.
 
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dacarter

Petty Officer 2nd Class
Joined
Mar 6, 2013
Messages
106
Re: Power loss VP 5.7 Gi-D (with Video)

Walt,

Thanks for posting the USCG confirmation that no anti-siphon is needed in my situation. (Tank below engine and all fuel components)

Forums like this are great as long as everyone keeps the right attitude and plays nice. I have serveral forums I read and participate in for each of my hobbies, and couldn't live without them.
 

dacarter

Petty Officer 2nd Class
Joined
Mar 6, 2013
Messages
106
Re: Power loss VP 5.7 Gi-D (with Video)

Just to confirm the cause of the original post for those that might see this later, the boat is now fixed! I water tested it yesterday and it planed out quickly, and ran up to it's 42 mph top speed quickly, with no sputtering or hesitation. Since I could blow through the anti-siphon valve with some effort and the ball didn't seem stuck, I am convinced it was the corroded distributor cap. I'll probably now buy the Volvo distributor cap and see if it seals better to the distributor than the NAPA, and keep the NAPA as a spare.
 
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