FP Regulator bad?

[salvageV6]

Follow the return line down from the regulator under the power steering pump where it goes from rubber to metal. It can get gunked up there as mentioned, and is a good one to widen out with the awl.

It uses the same fuel line O-rings and if you can get the lines separated is an easy first test.

If you jack the car up for access it's not too bad to get at, use safety jacks too, we don't want to have to repeat ourselves for a new guy.

 

[pacecarta]

all of feed line o-rings (x4) are same size (filter in and out , frame line to engine line connection , fuel rail input)
the return line o-rings (x2) are smaller than the feed ones (regulator , frame line to engine line)

bw 27478 available at parts stores




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[Pronto]

Stupid o rings suck. They fall off or get pinched. Dumbass design.

 

[salvageV6]

Dorman 80020 in the Help Section should have both as well.

 

[1BUICKTtype]

where are all the saginaw restrictions that i can bore out located?

 

[GNRick]

If it were my car I would try a known good fuel pressure regulator that was not crushed....and I would also replace the fuel filter if it's over 3 years old. My car has 200k miles....never had this fuel line restriction that people like to talk about. Oh, I have a stock cam and I see 37 psi with line on and 43 line off. This is a 6 psi drop, not 9.

 

[Boostrules]

If it were my car I would try a known good fuel pressure regulator that was not crushed....and I would also replace the fuel filter if it's over 3 years old. My car has 200k miles....never had this fuel line restriction that people like to talk about. Oh, I have a stock cam and I see 37 psi with line on and 43 line off. This is a 6 psi drop, not 9.

I'm curious what your vacuum is at idle. My numbers are also 43 line off & 37 line on with vacuum gauge reading 17 at idle.

 

[salvageV6]

Mine froze up in the winter with about 160K miles on it at that fitting, easy first test if it comes apart.

43 to 37 is what my 2 cars do with Accufabs, about 16/17 inches vacuum at idle.

 

[dennisL]

So I disconnected the return line above the axle and hosed (is that a word) it to a gas can. Still using the old 237 regulator and engine cold I got 51 psi (line off) and 42 (line on). Vacuum was 17 in/hg.
I feel like I'm chasing my tail with all the unknowns, Accufab is 19 yrs old, Bosch 237 top is crushed, electric fuel pressure gauge is inexpensive GlowShift, etc. So I ordered an adjustable FPR and mechanical gauge from Kirban. I might have them by next week, I'll keep you posted.

Thank you guys for the o-ring info. Over the years I've purchased o-rings then discovered the id is wrong or the thickness is wrong, or they're not Viton, etc. Armed with the correct o-rings I'll change the fuel filter while I'm waiting for the new stuff.

 

[Pronto]

Maybe it's time to start fresh with a Kirbans...

 

[dennisL]

I agree Pronto, if I had the original 233 regulator it would give me a baseline for troubleshooting but I can't find it. (Which pisses me off because the only GN parts I throw away are sparkplugs and oil filters.) The new adjustable FPR should do the trick. Even if it doesn't solve the problem I can proceed more confidently. Paul gave me enough info to tackle this thing and all you guys have been very helpful. To be continued .......

 

[salvageV6]

If your Accufab is only 19 years old it's probably still good.

But if it isn't they sell a rebuild kit for $25.

There's not much to them, any of them....

 

[dennisL]

I replaced the Accufab with a new Kirban regulator and got the same result. Then I disconnected the return line under the engine and ran the return from regulator into a gas can. Pressure now drops like it should (42 off, 32 on, cold engine)!! Sooo, the restriction is somewhere in the return line on the frame. While the below engine connection was off, I did the 'awl thing' to the pipe end on the saginaw fitting. This helped a little because with the return line connected pressure now drops to 36-37 with vacuum on. Before this I was 'stuck' at 40 psi (vac on and off).

I wish I could replace the return frame line with a new hard line but I'd have to separate the body from the frame to do it. So I'm thinking replace it with 1/4" hose. My problem is that I don't know to connect the hose to either the hard line below the engine or to the bottom of the regulator. This requires a hose-to-saginaw fitting. Anyone know where I can buy the proper adapter?

Again, thank you. All the responses have been very helpful.

 

[salvageV6]

I'd try some compressed air through the line first but probably would disconnect it above the axle again first to see if anything comes out (besides some gas).

You could visually trace the line and look for kinks etc.

Just re-read your post 36/37 may be good enough anyway to run it as is sounds about normal to me.

 

[dennisL]

I have visually traced the return line, as best one can while laying on their back. I ran my finger along along the pipe in the places I couldn't see very well. No indents or anything unusual. I think I will try the compressed air before I "throw in the towel" but I'm trying to plan my next move in case that doesn't work. Hey, do you know where I can get a 20 foot pipe cleaner? LOL

 

[dennisL]

Well today I opened the frame return line again and blew compressed air from the back to the front. While it was open I used a different awl (more gradual taper) at the saginaw fitting. Man that pipe end is small. The proper return line o-ring ID is much larger than the OD of the pipe end. Its 1/4" pipe but the end is much smaller. The hole at the end is only 7/64". I would love to bypass that fitting and have a true 1/4" return from the FPR to the tank.

Put it all back together and its still not right but better than before I started this project. Now with the FPR set to 43 (line off) it goes to 37 with vacuum line on (hot idle). I'll drive it tomorrow and see what the BLMs are now.

 

[1BUICKTtype]

how did this all work out for you?

if the restriction is the hose from the FPR to the steel return line connection by the frame up front, wouldn't it be possible to just change that section of the line to lets say an SS braided 6AN line and continue using the factory steel return line with no more high idle pressure problems?

 

[dennisL]

The restriction is not in the line from FPR to below the engine. That pipe is fine. It's in the next section that runs over to the passenger side then along the frame, back to the rear axle. My guess is that the restriction is the end of that pipe where it was crimped to make the saginaw fitting. As I said before, the i.d. of that end of the pipe is much smaller than the pipe end that goes into the bottom of the FPR, yet both are 1/4" pipes with crimped saginaw ends. And they are both original from the factory. My theory is all the original return pipes (except at the FPR) were crimped down too much, which wasn't a problem with the original low pressure fuel pump and FPR. But when you replace them with a higher volume pump (like Walbro 340) and adjustable FPR, now the BLMs drop way down because the fuel pressure is too high with vac line on.

In order to prove my theory, I'd have to cut off the end, then connect it to a new braided line going up to the FPR. I haven't decided yet if I want to do this, replace the entire line that runs along the frame, or replace both lines (from FPR to rear axle). The first option is certainly less expensive.

Oh, what I did for a temporary fix was make changes to the chip so less fuel is supplied at idle and while driving. (I make my own chips.) The BLMs are back to 128 +/- 4 but I'm still going to replace the "restriction" with braided hose, probably 6 AN. A 4 AN will probably work fine for my street driver but I believe the correct adapters are only available in 6 AN.

 

[pacecarta]

the line at regulator that runs down engine is not 1/4" thats why the hole is bigger ,
the frame line is 1/4" and that saginaw end by engine is the worst restriction

 

[Anthony P]

@dennisL, you're on to it as you note in post #38...the limitations of the stock fuel lines are exaggerated when the stock fuel pump is replaced by a larger pump (and hot wire kit) and the engine performance level does not utilize the increased fuel capacity and has to return the unused fuel to the tank.

drill out the saginaw fitting in the return line using a 9/64" drill bit. then blow out and flush the line from the tank end so as not to pass the drilling chips through the line.

another member, @Tori, went through a similar scenario as you and documented his efforts, including drilling out the fitting.

see it here (drilling out the fitting is not discussed until post #46-47)

https://turbobuick.com/threads/adjusting-bosch-233-regulator.449410/