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Fuel Pressure

DieselCash

DieselCash

Trust but, verify
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Location
Salado, Texas
I finally purchased a fuel pressure gauge for testing purposes on my truck. The other day when I tested my fuel pressure it seemed to run very low. My lift pump is also starting to make noise. My lift pump is about 1 year old plus a couple of months. So I will share with you how I got my test pressure and see what you think.

Here is my new pressure gauge hooked up to the water drain;

IMG_1277.jpg


Under this cover is how you get your lift pump to run from under the hood;

IMG_1278.jpg


Once you get the cover off, under it on the far left is the fuse for the lift pump, pull it our of its cover and touch the metal end to one of the hot bolts. Once you do this your lift pump will start working. Here is a picture of how it is done;

IMG_1279.jpg


After starting the lift pump I got 6 to 6.5 pressure on my gauge. This is before I ever even started the truck, just the lift pump. Here is a picture;

IMG_1280.jpg


Next I started my truck and read the pressure. It was at 1.5 pressure, which to me on a running truck is very low. Here is a picture;

IMG_1281.jpg


Then I turned the truck off and the pressure was at 5 PSI.

IMG_1282.jpg


I repeated all these steps with the fuel cap off and none of my pressures changed. I plan on replacing my factory style lift pump with a Walbro. I have a thread running now asking for vendor support.

Here is were it gets good, my truck back in the day had a secondary tank. I still have the switch under the truck from it. Should I remove it and if so do you think it will help? Here is a picture;

IMG_1284.jpg


Here is a pic of my factory lift pump;

IMG_1283.jpg
 
check your filter that's the pressure before it goes to the filter. also could be sock in tank not letting enough volume thru it. Sounds like pump might still be good worth a try anyway
 
Like I mentinoed in the other thread that you Hijacked :)...

I can almost guarantee you have zero pressure at the Injection pump.

Blow tank sock clean and try again. IF still no-better, and you have a rubber press fitting for the gauge (blow gun tip style), pop off the LP outlet and stuff it in there and have someone energize the LP and see what you get.

When I had 4 at water drain idling, I had 1.5 at IP, and it went to zero very very easily. My filter was brand new, as I suspected it was the filter. This was with my old stocker LP when I was awaiting walbro replacement.
 
I will have no air pressure till I get back home in mid December. I will do the air blow thing once I get home.

I will try the pressure on the other hose tomorrow.

So the best place to get your pressure is before the filter manager?
 
DieselCash said:
I will have no air pressure till I get back home in mid December. I will do the air blow thing once I get home.

I will try the pressure on the other hose tomorrow.

So the best place to get your pressure is before the filter manager?
Click to expand...

Best place to get pressure is after the flt manager before the IP. This way you know exactly that you're IP is getting fed.

However its tough to access unless you T off the line and run a length of hose out the valley with the intakes off.

Testing it before the FLT MGR or Water Drain, or bleeder screw will all read pre filtered measurements.

I recommended testing at the LP ass just so you are ruling out the hose in between LP and Flt MGr.

If you have pressure there, but not at water drain, you know where the problem is.

If you have NO pressure at LP ass, and you blew lines clear, you know LP is garbage. (Or a poor line between LP and tank, but that would probably result in air entry into system).

Doesn't take much air to blow the sock clean...

Also good idea to wait till your tank is near empty before doing any LP work if possible to avoid the diesel bath.
 
You can T in in the short horizontal part of the fuel line just before the IP inlet,simple and fast,no need to remove anything else.
As they said,either a restriction upstream of the LP,or the LP aint putting out.
I would eliminate that sec tank valve set up first,it may be your prob.
 
Wow that tank valve is $80! :eek:

Maybe I will remove that tomorrow. :thumbsup:

I never plan on putting a second tank on my truck.

What size is the fuel line in the valley? Maybe tomorrow I will pick up a brass T.
 
IIRC TD said he could blow back to the sock with just lung pressure was enough to make it go again for awhile.
 
DieselCash said:
Wow that tank valve is $80! :eek:

Maybe I will remove that tomorrow. :thumbsup:

I never plan on putting a second tank on my truck.

What size is the fuel line in the valley? Maybe tomorrow I will pick up a brass T.
Click to expand...
I think i used a 1/4 ",not sure if i drilled it up a size either,its been a while:smile5:
 
ak diesel driver said:
IIRC TD said he could blow back to the sock with just lung pressure was enough to make it go again for awhile.
Click to expand...

I've done that a few weeks ago on the side of the highway... Even though I didn't think I got any in my mouth, I was burping up diesel smell for hours, absolutely disgusting. I dont' recommend it. But it works.
 
The hose from the filter manager to the ip is 1/4". I just put one on my 93 engine yesterday.
 
Well I got the fuel tank switch valve out. In the process I took a Diesel bath. But, I got it out along with all the switch in the cab and all the wire. It started getting dark so I was unable to test it afterwords.

It only gets better! :thumbsup:

I also locked my keys in the truck. So the wife is mailing me the spare keys. I will be without a truck till the end of the week. Anybody know a way to break into a 1993 Chevrolet? :mad2:
 
bk95td said:
The hose from the filter manager to the ip is 1/4". I just put one on my 93 engine yesterday.
Click to expand...

Thanks! :thumbsup:

I will do mine next weekend if I get my truck unlocked.

Did you have to take anything apart to install it? :confused:
 
DieselCash said:
Well I got the fuel tank switch valve out. In the process I took a Diesel bath. But, I got it out along with all the switch in the cab and all the wire. It started getting dark so I was unable to test it afterwords.

It only gets better! :thumbsup:

I also locked my keys in the truck. So the wife is mailing me the spare keys. I will be without a truck till the end of the week. Anybody know a way to break into a 1993 Chevrolet? :mad2:
Click to expand...

Yes, make yourself a slidelock tool with a coat hanger.

Striaghten it out, and put a 90 degree bend about 4 inches from the bottom.

Wrap ducktape sticky side up around the flat bend, then secure it with normally applied tape, making the 3" bend stickly.

Wedge window open a little, and lower the tool about center of door.

When lowering the tool with the small bend down first, you will feel it clear the bottom of the window, then twist it so it turns inward a little.

WHen it is inward a little go down a tad more and it should be landing on the doors locking rod, at this point you should see the lock move/jiggle on the inside, as you are looking through the front window as your are working the tool from the side.

Work it a little until it unlocks.

Open door, get keys.

Work tool outwards easily.
 
http://www.z-tool.com/Kits.htm

The bottom left corner of the picture of the kit is the real slidelock tool. Make yourse similar.

In case it wasn't clear, you lower this rod in the center of the window where you see them put the 'slim jim' down the window in the movies.

However, slim-jim's are only for 'pop locks', not GM's, where they have 'slide locks' (horizontal movement to lock/unlock the lock cam)
 
DieselCash said:
Thanks Matt! :thumbsup:

I will try what you stated above, wish me luck! :mad2:
Click to expand...

Doesn't take much force, so don't use force. Key is to watch the inside as you're working the tool, The rod is only a few inches lower than the bottom of the window when you're 'feeling' for it. LIke I said, watch for it to 'jiggle' or move a little bit, when it does, you're close. To unlock it, you need to make it do a horizontal movement.

There is also a triangular shaped weld on the rod that the tool will catch if slid into it. THis triangle is there for this exact purpose, to ALLOW someone to unlock the truck, AAA, Locksmith, etc.

You may need to let the tool ride over that hump and get it from the other side, however the sticky duct tape backwards will probably create enough friction to grab it anywhere on the rod, depending how tight or loose your locks are.

ONe more thing, don't go trying to work the tool right where the lock is physically on the inside of the door. You need to be more towards the rear of the vehicle, basically catching the connecting rod between the up/down paddle lock and the locking mechanism towards the rear of the door.

You can probably just pull the rubber seal right up and off the door (I can on mine) and you wont need a wedge, this will probably let you look right down in there too, perhaps even seeing the rods with the light.

Keep in mind there are 2 rods passing through there, one for the handle, one for the lock. So if your fighting the top one too long, and dont see the lock jiggling from inside, work the tool around the top, and move down to the next rod, the jiggle movement should be obvoius you're on the right one.
 
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