Gas Regulator Pissing at set-point Threads-1987 454 Holiday Rambler-Alumilite

[lngfish]

Good Morning,

I have been reading up on this from this site and other sites.

Well as I can see and have read it is hard to remove this regulator but the bonnet of the regulator is easy to remove where it sits in frame with 4 allen head screws.

Yesterday I removed the inline small filter in the main fuel line 12.7 mm (1/2") and installed a hosed at both ends pressure gauge (0-15 psi), using a 3/8 T and bushing reducers to 1/4" NPT nipples. And installed it to get a before I mess with it main line pressure. It read 6.2 psig.

This will only be temporary and a good location to put it to get a reading.

I have read that these regulators are Holley 12-830 (valve) and repair kit is 12-807 (kit).

1.Does anybody know if I can just swap out bonnet assemblies to eliminate dropping the tank?

2.Should I love main line pressure to 5 psig after I install the new bonnet? or new valve.

3.If I have 6 psig on the main 1/2 supply line won't the mechanical pump add more pressure?

4.Is there any real purpose of the mechancal pump? or it there just for looks? It doesn't seem to me it serves much of a purpose cept allow recirculation.

Thanks!

[DaveVA78Chieftain]

It is a very long distance from the tank to the mechanical fuel pump so the electric one is used to get the fuel to the mechanical pump.

Mechanical pump performs it's own pressure regulation.   It will not amplify (add to) the electric pumps pressure

Please read this posting about someone who just rebuilt his delivery system: http://www.irv2.com/forums/f65/is-this-the-electric-fuel-pump-on-88-southwind-165403.html
There is several pictures on page 2 of that thread.

Dave

[lngfish]

Dave,

I tried that link and it seemed to DL but very slow. I will try tomorrow. Thanks for letting me know the mechanical pump will not add to pressure. I will need to put a temporary gauge at carb somehow or at mechanical pump outlet. I think it needs to be 2-4 psig. Is 6 psig ok in main line?

This rig has 78K on it and the mechanical pump is original and on unit since 1987, so 26 years but seem to run OK and I can feel in inlet to mechanical pump pulsate so it is doing it job. Would it be a good idea to replace Mechanical pump and will engine run on just the electric pump of Mechanical pump shoot the bed?

[bluebird]

I would replace the mechanical pump if it's original. The diaphragm is brittle and can start leaking at any time. If it leaks inside, it'll fill the crank case full of gas, dilute the oil and poof, there goes a good engine.

Much easier to do it under controlled environment than on side the road someplace.   

[lngfish]

Thanks for feedbacks. So far no gas in crankcase but I see your point. Where is a good place to get a good quality mechanical OEM pump besides the dealers? Are they hard to install? Any tips on installing a new pump?

[bluebird]

I bought the one for my old Itasca at O'riellys . They had two different pumps, different boxes. One was 1/2 price of the other, both had the same warrantee. I said let me see um both, they were the same pump exactly. I asked the counter guy, which one would  you buy? He just smiled. So far I've had good luck there.

[DaveVA78Chieftain]

My 84 Service manual says Fuel pressure at a Quadrajet carb should be 5 1/2 to 7 psi
However, the Chev MH Service manual says 1 1/2 to 5 psi
Based on my what I read in my How to Rebuild and Modify Rochester Carburetors book, I would go with the 1 1/2 to 5 psi value.  They say volume is the key to keeping the fuel bowl full, not pressure.

2-4 psi values are normally for generator carburetors.

[lngfish]

OK Dave and Bluebird,

I will get at AutoZone, Advance, or O'reillys.   
What sort of price might expect. It looked like $80 or so.
Will these really fail and flood the crankcase with gasoline?
So If the mechanical are self regulating, the only input I will have is adjusting the main fuel pressure regulator back at the tank correct?
Before I start my work I intalled a pressure gauge jig (temp thing) where the filter goes. Easy to install and read.

I got a 6 # reading there and unit ran well.

Hopefully my Holley Kit will have same diaphram as the OEM one and tomorrow it will be a 30 min fix to just replace the diaphram that is leaking causing the pissing at the set point threads and lock nut arrangement.

Wish me luck. I will report back if I'm sucessful. The kit was $10 at advance, made by Holley. The valve was $40. I wil return valve if diaphram/spring kit fixxes leak.

Steve

[DaveVA78Chieftain]

Please let us know how the kit works out.   I am sure others would like to know that for reference.

Dave

[Lefty]

If the diaphragm in the old mechanical pump fails, it most definitely will fill up the crankcase with gas.

Deleting the mechanical pump is not recommended UNLESS you replace the stock in-tank pump with a high performance fuel pump that can push the fuel all the way to the engine at the proper pressure/volumes by itself. The in tank pump was added to cure a fuel vapor lock issue, and was never intended to be the main fuel supply pump.

[lngfish]

The kit worked perfectly!

Tips:

1. Soak the screws overnite with penetrating oil. They are very fine threads.
2. No open lites when you remove bonnet assembly with diaphram gal will some out.
3. I used old spring not the new kit spring. The kit has 2 springs, HP and LP. The spring used in this application is the HP spring; (NOT RED), plain metal is correct spring. The HP spring is the longer spring.
4. Reset pressure at 5 psig when all done. Just turn the key on and off like 10-15 times real fast, get a helper. Hard to set with engine running as there is too much pulsations. I used my Wife at the key and my 8 year old grand daughter reading the pressure gauge on her back. She did great.

(I installed a gauge removable Jig where the Main Fuel Filter. Advance Auto Parts had a 0-15 psig Mr. Gasket Pressure gauge for like $18. 1/8" male NPT out the back. I got the necessary pipe fitting at Ace hardware. 1/4 male nipples fit tight into the 1/2" ID rubber fuel hose. I used a 3/8 Galvanized T, (2) 3/8 - 1/4 " NPT busing reducers, and two 1/4 NPT nipples. Pull your filter assembly out ant take to hardware store.)

I will be able to return the Regulating Valve now and the kit is used now.
                   
A.Repair Kit information: 
                               
Holley: Regulator Diaphram Repaiar Kit 12-807
Advance Auto Parts: Regulator Repair Kit 12807 (no-dash)
Advance Auto Parts Number: 22311628
Just ask the counter guy to look up 12807
Not sure what the 22311628 number is but is on my receipt.
$9.99

B.Entire Regulator Valve:

Holley Part Number 12-803
Advance Auto Part Number 12803
Advance Description: "HO FUEL PUMP" !!
(Is it not a fuel pump but fellows at counter were not interested in correcting Corporate. Anyway if you get at Advance Auto Parts expect for it to be ID'd as a "fuel pump" well a "HO FUEL PUMP".

(The fellow at the counter was smart he told me to order the Pump and you may get a regulator. He was correct. I owe him one)

I'm happy this worked for me and hopefully helf a few others out for a fix when you have gas spewing out the set point threads where the setting lock nut is.

BTW the old diaphram had a pinhole leak in it, barely noticeable but there. Diaphram sort of fragile and dried out.

Next step find a good mechanical pump.

[DaveVA78Chieftain]

Great!  Gotta love it when it all works out as planned.