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Fuel bleeding
- Thread starter TexF18
- Start date
- 6,860
- 9,500
- 113
- Location
- Papalote, TX
Have you removed the two check valves directly in front of the fuel tank?
Also have you drained the tank and filled it with fresh fuel? Checked to make sure the fuel pickup sock is not plugged?
Be careful if you decide to pressurize the fuel tank or blow back through the feed hose to the tank, use only low pressure.
Also have you drained the tank and filled it with fresh fuel? Checked to make sure the fuel pickup sock is not plugged?
Be careful if you decide to pressurize the fuel tank or blow back through the feed hose to the tank, use only low pressure.
- 6,860
- 9,500
- 113
- Location
- Papalote, TX
You should have also replaced the filter
- 6,860
- 9,500
- 113
- Location
- Papalote, TX
Yes, I just wrap a red rag around the blow gun in the fuel fill pipe, that way I can only build 4-5PSI max which is all you need if the check valves have been removed, I would not even try it with the valves in place, too much pressure you can blow the vent line off the top of the tank. 30 psi might even rupture an older tank.
After spending the big bucks for a new or rebuilt IP I would replace the filter even if it was only a week old, along with all the rubber lines.
After spending the big bucks for a new or rebuilt IP I would replace the filter even if it was only a week old, along with all the rubber lines.
- 2,953
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- Olympia/WA
Should also verify that the fuel lift pump is working.
Gamble
Well-known member
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- Los Angeles, CA
I would suggest removing the check valves at the right rear of the truck near the fuel tank. I would do that before any other troubleshooting. It worked for me and I hope it works for you.
Thumper580
Active member
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- Virginia
Yes, get rid of them. When they sit for years they get stuck and problematic.
I agree with Coug.
If all you did was change the injection pump and you're now not getting fuel to the filter when cranking, it suggests to me that your lift pump isn't working.
I've never personally had any problem with my check valves but I've had lift pumps fail repeatedly. It was running before the IP change? (you changed it because of a leak on the IP, right?) I don't see why changing your IP would make your check valves fail. But it is possible for an IP to pull fuel from a weak/failing lift pump and the engine still run. Introduce air by changing the pump and it makes sense what was limping by before now doesn't work.
Pull the outlet line off the lift pump and crank. no fuel? replace.
I would pump an (empty) water bottle of fuel out of the lift pump and another bottle out of the filter to make sure it is clear/pristine before I would let any hit your new IP.
papakb
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- San Jose, Ca
It's worth remembering that not all of us are driving the newer trucks and the older models didn't include check valves. For a new member this could be a point of confusion. The other thing is that pressurizing the fuel system above a certain point is potentially harmful. Overpressurizing old fuel lines and diaphragms isn't a good idea and new owners would probably tend to exceed that ~5psi limit pretty easily. This is one of the reasons I built the simple vacuum bleed system I did. It draws the fuel up from the tank rather than trying to blow it up. Hooked to the water seperator it only takes about 15 seconds to draw fuel. If it doesn't then there's either a clogged line or the pickup screen is blocked or missing.
- 6,860
- 9,500
- 113
- Location
- Papalote, TX
When did they start installing the valves?
Both my 92 and 93 had them, every other one I have worked on was newer and all had them.
Gamble
Well-known member
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- Los Angeles, CA
The check valves are before the lift pump in the fuel feed and there is no cost to deleting them, other than a few inches of fuel tube from the parts store and some clamps. That's where I would start if I were you before replacing the lift pump IF you've always had this problem. Otherwise, I agree that the new IP would not impact the check valves. One way to check if you're getting enough fuel is to open remove the wire on the IP (I'll have to look at the TM as I don't remember the wire # off hand) so that you can open the valve behind the driver side wheel and when the truck is cranking you can see if you're getting a steady volume of fuel.
It's 99 m1123. Will check for check valves and rubber on the lines on the back of the truck. Is there any harm in deleting the checks or just clean out or replace. All the lines fuel lines around the motor have been replaced within the last few months.
Lastly I like that vacuum pump setup. Do you have a link to the pump
Lastly I like that vacuum pump setup. Do you have a link to the pump
papakb
Well-known member
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- San Jose, Ca
The pump is one I found at a local flea market for $10 but it isn't anything special and any small vacuum pump will work. In this application you could use a small air pump and just plumb the intake to the bottle rather than the air outlet. You can find small pumps in 24 volts too. The real secret is drawing the vacuum on the mason jar and then sucking any fuel into it and not into the pump.
- 6,860
- 9,500
- 113
- Location
- Papalote, TX
They are not on the back of the truck, they are in front of, almost on top of the fuel tank, removing these are one of the first things just about everyone does because they are so problematic.
Just do one at a time so you do not get the lines crossed.
Thumper580
Active member
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- Virginia
You need to get a foot of 3/8" ID and 1/4" ID fuel line and clamps. Remove the check valves and replace with the rubber fuel lines....
DIVE DIVE
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- Chesapeake, VA
This might work too. It’s just a Gatorade bottle with a hole drilled in it and sealed with tape, then hook up the old shop vac. This is how I primed my fuel system.
Sucked from the filter outlet just upstream of the injection pump.
Sucked from the filter outlet just upstream of the injection pump.
- 6,860
- 9,500
- 113
- Location
- Papalote, TX
Only a slight chance of explosion, many shop vacs have brush type motors
- 2,953
- 4,297
- 113
- Location
- Olympia/WA
Diesel vapors are nowhere near as volatile as gasoline vapors are, so the risk of explosion is almost non-existent for just having the little sparks created by a brush type motor and the few vapors being released from unheated diesel fuel.Only a slight chance of explosion, many shop vacs have brush type motors
I would definitely NOT recommend this method for a gasoline fuel system.
Another approach with a (clean) shopvac is to use the output side of the vac to push a little extra air into the tank filler neck vs. trying to suck fuel from the lines. I've done it. Worked great for me. No gatorade bottle required.