Will Increasing Fuel Pressure Increase O2 Readings

[Rodney87GN]

Ttype6 mentioned about a possible leak inside the tank...which is usually a bad or ruptured fuel hose inside the tank....the one that connects the fuel pump to the sender. When you installed the Walbro it should've come with the special rubber hose that's rated for submersion in gas that you must use...you cannot use regular fuel inj hose, or will turn to mush and fail.

 

[trbojo]

AH HA MY FRIENDS!!!! sounds like we may be on to the potential source of the problem.....fuel delivery....

 

[trbojo]

I'm not claiming to be an expert or know more than anyone who has posted before me, or say that any of these other guys are wrong, but i would double and triple check vacuum leaks first, then verify a properly working gauge and regulator, then check the hotwire and voltage drop at the pump. These are easy and CHEAP!

Again I'm not saying anyone else is wrong, but it wouldn't take much time to do all of these first, and if i'm not mistaken all could contribute to your issue. Combining any of them would only compound the situation. Pro's and more experienced folks correct me if i'm wrong.

well said my friend.......

 

[NorEaster]

Run off the fuel rail to the windshiled through fuel injection hose. Is this ok?

Otherwise, the guage is usually attached to the fuel rail and can only be checked when parked, idling and hood

I haven't had any luck using a rail mounted gauge. I would double check the another gauge like a rent a tool at auto zone. Sounds like you are on the right track. Good luck.

Sent from my DROIDX using Turbo Buick. please mind the auto-correct

 

[Ttype6]

Per turbObuick57, I included what I was using to monitor fuel pressure.

Run off the fuel rail to the windshiled through fuel injection hose. Is this ok?

Otherwise, the guage is usually attached to the fuel rail and can only be checked when parked, idling and hood up.

I have noted in previous threads that my fuel system does not maintain pressure after being parked. For example, it has been over an hour since I drove the vehicle and now the fuel pressure guage is reading less than 20 psi. Is this normal or an indication of where my problem might be?

Thanks
Matt

What you did is correct. You have a fuel delivery problem. Check some of the things I talked about and we can eliminate them one at a time. Do the things,first,that cost nothing and are the easiest,then post what you did. The easiest things will be the visual inspections.

 

[mmarlett]

I have an update.

First, I checked for vacuum leaks and did not locate any.

Second, I checked for corrosion around the alternator and fuel pump connections related to the hot wire kit; everything looks brand new.

Third, I cleaned the ground location on the frame for the hotwire harness/fuel pump under the rear bumber. Just a precaution as it all seemed fine.

Fourth, I checked the fuel pressure regulator by using the recomended compressed air check (very smart). Adding 20 psi of air did jump the fuel pressure guage to 60 from 40 psi. FPR good.

Fifth, I did a voltage check at the fuel pump wire leading into the fuel tank and read 14.2 volts with the engine running. Voltage good.

The good news is the advise I recieved from this forum helped me get this far in my diagnosis. I would not have known how to rule these items out without the input. Thanks!

The bad news is that I will need to continue to trouble shoot.

Next:
- Fuel filter (current one was changes 3 years agao and 8,000 miles,
- Drop the fuel tank and check for internal leaks from pump/plumbing.

Any additional thoughts are welcome.

I will keep all posted on my finding.

Matt

 

[Ttype6]

Next:
- Fuel filter (current one was changes 3 years agao and 8,000 miles,
- Drop the fuel tank and check for internal leaks from pump/plumbing.

Good Job. I'm assuming you saw the same numbers on the gauge. If that's the case,remove the filter and see if it has a lot of resistance when you blow through it. It will have more at first while there is still gasoline in it,but should get better as you blow gas out of it. It should be very easy to blow through. If it's very difficult to blow through,get a new AC Delco.

 

[LITLV6]

you could have had some trash in the bottom of your tank and the strainer in the bottom the tank be plugged up or the filter being clogged (been there, done that.) I personally have an 86 with TT chip and siemens 60lb. injectors running 23lbs using 100 octane. I wouldnt have bet on the regulator being the issue so much but as i was chasing a gremlin in mine a replaced mine with an accufab and it was money WELL spent. i'm betting you have a clamp missing or lose on the supply side of your walbro or strainer collapsed or plugged up or filter. filter would be my first choice then drop the tank.........

 

[Ttype6]

Next:
- Fuel filter (current one was changes 3 years agao and 8,000 miles,
- Drop the fuel tank and check for internal leaks from pump/plumbing.

Any additional thoughts are welcome.

Where is your chip enrichment at now?
How much spark retard did you see?
What O2 Numbers?
Did you see the same fuel pressure at WOT?
If you did,remove the filter and blow through it to see if it has a lot of resistance. If it does,get an AC Delco.

 

[Kent Buckles]

I had the same problems and symptoms two weeks ago a few hundred miles from home. In my case ended up being the pump to sender fuel line inside the tank. If the fuel filter is ok, my guess is that you could have the same problem as I did considering you have eleminated most other potential failures. HTH

 

[trbojo]

could very well just be a bad pump also...it is possible to get a normal pressure reading with not enough volume...there were problems with early Walbro 340 pumps...i had one that would drop about 5 psi after it got hot...replaced it with a Red Armstrong XP..

 

[mmarlett]

New posting from tonights events.

First, thanks to all for the continued help!

Tonight I changed out the fuel filter with a new AC Delco piece. The replaced one, only had 8,000 miles on it and seemed fine. I still did the change.

Next, I saw a comment on a previous post on how to check for a failing fuel pump or low fuel supply from the tank. Prior to dropping the tank, I preformed this simple test. The post said to have the engine on, turn up the fuel pressure regulator to 100 psi and monitor the fuel pressure guage to see if the needle climbs that high, falls short or starts to flutter. If the psi is not achieved or the neddle starts to flutter, the presumption is the fuel pump/supply from the tank has failed.

Here is were I need your help interpreting my findings. I could NOT increase the fuel pressure regulator past 58-60psi. Specifically, I lossend the nut all the way to the top, then turned the bolt/adjuster all the way in. Again, it would not exceed 58-60psi.

Next, I again did the test I tried last night were I set the fuel pressure regulator to 40psi line off and then added 20 psi of compressed air to a total of 60 psi that did register on the fuel pressure guage. This time I increased the compressed air to 30 psi (40+30=70) but the fuel pressure guage did not exceed 58-60psi. I then increased the compressed air to 40 psi (40+40=80) but the fuel pressure guage did not exceed 58-60psi. Finally, I increased the compressed air to 50 psi (40+50=90) but again the fuel pressure guage would not exceed 58-60psi.

Prior to tonight, my next step was to drop the fuel tank per above advise. With this new information, am I correct in concluding the fuel pressure regulator is the problem?

If so, I am dissapointed. I added this Accufab fuel pressure regulator within the past 3 years and 5,000 miles and have never had the positive experience of achieving a great performing turbo Regal as I have been chasing this tune all over.

I appreciate further advise.

Regards,
Matt

 

[Ttype6]

With this new information, am I correct in concluding the fuel pressure regulator is the problem?

No,this is more proof that it's time to go into the tank.

Look at you,thinkin and everything. I saw this same post. Good job.

 

[trbojo]

bad pump or problem in tank...

 

[mmarlett]

Thanks to all for keeping me pointed in the correct direction.

I will drop the tank and watch for those things others have posted above.

Once I am in the tank, is there a way to test or confirm if it is the pump is bad or good, or do I just get a new one if I do not see anything else suspicious regarding the tank?

The pump was one of the first things I did replace; maybe 24 months ago. I did but a Walbro. This was supposed to be after all the Walbro issues were resolved (per my research on this site). I do have the receipt for this.

Thanks
Matt

 

[trbojo]

i would have a new pump on hand while you have the tank down...no sense in dropping it twice....if you don't see anything obvious, replace it...

 

[Ttype6]

i would have a new pump on hand while you have the tank down...no sense in dropping it twice....if you don't see anything obvious, replace it...

Good point,I have one of the new design Walbros I would sell you.

 

[mmarlett]

Ttype6,

Thanks, I may take you up on that offer depending on what I find.

I will try to get the tank down this weekend. If I do not find anything obvious, the car will sit with the tank off until I can get a new pump.

I will keep everyone posted.

Thanks!
Matt

 

[Ttype6]

Ttype6,

Thanks, I may take you up on that offer depending on what I find.

I will try to get the tank down this weekend. If I do not find anything obvious, the car will sit with the tank off until I can get a new pump.

I will keep everyone posted.

Thanks!
Matt

I don't recommend one of these new higher volume pumps. You'll probably not be able to get your fuel pressure low enough at idle because the return line wont be able to accommodate all the extra flow that has to go back to the tank at idle. The other problem with these higher volume pumps is that because they flow so much more fuel and the motor still uses the same amount,more fuel is returned to the tank. What you end up doing is sending a lot more fuel to the motor,that doesn't get used,and gets heated up before it goes back to the tank. Your just,needlessly heating up the fuel.

If you want to buy a new pump,I recommend an XP from Red Armstrong.

I have no need for this pump and would like to see it find a home. It will support 500 plus horse power with a volt booster. I always recommend a volt booster.

If it looks like you're gonna need it,its here.

 

[mmarlett]

Well, the kids and wife went to grandmas tonight; so under the car I went to drop the tank.

Please see attached pictures of my Walbro pump. These are pictures of the pump after being pulled from the tank. How does it look? Anything obvious that does not look correct?

I inspected all fuel lines going into the tank; all look good.

I inspected the wires going into the tank; all look good.

I inspected the fuel lines and rubber hose in the tank; all look good.

I inspected the fuel filter sock and filter screen at the bottom of the pump; all look good.

However, I believe this part may be important. I was surprised at how flat the sock screen was when I pulled it out. I then measured from the bottom of the fuel pump screen as it is installed on the pump to the top of the fuel pump unit lid that seals with the top of the fuel tank. It measured 8 1/8". Hmmm. I then meaured on the gas tank from the top seal to the bottom of the fuel tank, 8 1/8". According to my multiple measurements and visual inspection, I believe this screen was compressed againt the bottom on the fuel tank. This seems way to tight to allow adequate fuel to the pump under increased boost (the problem I keep having). There are to small plastic pieces in the pump filter sock to keep the sock seprated, but they seem they would not help in this situation. Since I cannot make this measurement with the pump istalled, it is hard to confirm.

Tell me I am crazy and this should not be the reason.

Now, how to preoceed???

Thanks!
Matt