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Username Post: no fuel to injectors        (Topic#361509)
Johnnycam 
Newbie
Posts: 7

Reg: 06-24-20
06-24-20 05:18 PM - Post#2797122    

If I had hair...I'd pull it out!
1988 Silverado LWB. 350v8. Suddenly wont supply fuel to injectors. Nothing had been done to it in the way of mods or upgrades.
Here's what all I've done...

Truck will turn over but won



 
Lead sled 
Frequent Contributor
Posts: 2019
Lead sled
Age: 60
Loc: Walton,NY.
Reg: 11-04-09
06-24-20 07:05 PM - Post#2797128    
    In response to Johnnycam

Probably a bad pump????????

Late yr model (Dec. 51 BelAir/ 52 trim), with a basically stock 67 Camaro SS350/295hp Turbo Fire Edelbrock 1405, Saginaw 4spd/355 geared 55/6 Chevy rear.2,1st place,and 1 top five award trophies so far
http://www.picturetrail.com/bris51deluxe


 
thx1138v2 
Contributor
Posts: 211

Reg: 05-01-14
06-24-20 07:52 PM - Post#2797130    
    In response to Johnnycam

Or a clogged fuel filter. Might be time for a new one anyway.



 
someotherguy 
Senior Moderator
Posts: 29177
someotherguy
Age: 50
Loc: Texas
Reg: 08-01-03
06-25-20 06:06 AM - Post#2797141    
    In response to Johnnycam

I'm confused as to why you would replace all those other parts (except the pump) when it's clear the engine has spark and will run when you pour fuel into the TB.

There's a no-start troubleshooting write-up linked in the FAQ post at the top of this forum.

No fuel spraying out when you pulled the line loose generally will lead you to a bad pump, or at least a failed ground wire from the pump to the frame, or ... please see the FAQ

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
Johnnycam 
Newbie
Posts: 7

Reg: 06-24-20
06-25-20 09:13 PM - Post#2797213    
    In response to someotherguy

I pulled the wire harness from the pump at the tank and didn't get a positive test light on the harness 12volt wire going to the pump, I considered it wasn't receiving voltage to the pump.



 
Johnnycam 
Newbie
Posts: 7

Reg: 06-24-20
06-25-20 09:15 PM - Post#2797214    
    In response to Lead sled

I pulled the wire harness from the pump at the tank and didn't get a positive test light on the harness 12volt wire going to the pump, I considered it wasn't receiving voltage to the pump. I hope its something else with a full tank. But a pump has been ordered. I was looking at the schematic and even a low/bad oil pressure switch can disable the pump. Never knew how many "players" were involved with the fuel pump operation!



 
Johnnycam 
Newbie
Posts: 7

Reg: 06-24-20
06-25-20 09:17 PM - Post#2797215    
    In response to Johnnycam

Can I momentarily hook the new pump to the harness and check for operation before I have to drop the tank/or raise the bed?



 
65_Impala 
Very Senior Member
Posts: 4494

Reg: 12-29-02
06-26-20 09:40 AM - Post#2797238    
    In response to Johnnycam

The oil pressure switch is not the cause of the pump having no power unless there is already another fault in the pump wiring. The OPS is a backup, you can disconnect it and the engine should still run. I have deleted it in swaps without any issue or having to do anything else to make the pump still work.

Buy another pigtail repair connector and put power to the pump and see what happens.



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3861
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
06-26-20 02:06 PM - Post#2797249    
    In response to Johnnycam

There will only be power to the fuel pump for a few seconds when you first turn the key to the on position. If you are turning the key on then walking around the vehicle testing for voltage to the fuel pump circuit, there will be no voltage, and should not be power to the pump after a few seconds.

The truck has a fuel pump relay that supplies power to the fuel pump when:
- Anytime the ECM receives a distributor reference pulse. (Engine running / engine cranking)
- The key is turned on engine not cranking

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
CowboyTrukr 
"9th Year" Silver Supporting Member
Posts: 4432
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
06-26-20 02:18 PM - Post#2797251    
    In response to Chevytech

X2 on the oil switch. Mine failed to grounding internally. Would start and blow the fuse as soon pressure got above ~10psi because it would close on the grounded contact unplugging gave me the ability to drive home.

Greg

'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500
'00 Explorer XLT 4.0 V6 Auto
'94 K2500 5.7 NV4500 ECLB - SOLD
‘87 GMC S15 SCLB 4.3 Auto - SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
wagonman100 
Super Senior Member
Posts: 14562
wagonman100
Loc: Baltimore, MD
Reg: 11-27-04
06-26-20 08:39 PM - Post#2797275    
    In response to CowboyTrukr

If you don

Jay
Friends don’t let friends drive Fords.

1999 Silverado Z71 4X4 extra-cab short bed
1983 Malibu Fauxmad - tubbed
1978 El Camino Kustomized
1972 Monte Carlo
1957 210 handyman wagon
1957 Nomad sport wagon
1957 Cameo Carrier


 
alpinecrick 
Newbie
Posts: 19

Loc: Western Slope of Colorado
Reg: 07-11-17
06-26-20 09:00 PM - Post#2797278    
    In response to thx1138v2


Partially plugged or plugged fuel filters are the primary reason these pumps burn out.

Change the fuel filter every 15K-20K, and the fuel pump may outlive the motor........



 
djw1960 
Poster
Posts: 56
djw1960
Reg: 09-10-14
06-27-20 12:08 PM - Post#2797309    
    In response to Johnnycam

I have a 1988 C1500 with a 350 too. It sat for about 5 years, before trying to get it started again. I had a similar issue to yours. I first disconnected the fuel line after the fuel filter to see if fuel was getting thru it, and collected a 12 oz bottle of fuel pretty quickly, so reconnected it. Then went to the back of the TBI and disconnected the fuel line there, and once again filled a bottle with fuel. I then pulled the air filter and so that I could see the fuel injectors. I had my son turn on the key to see if any fuel came out while trying to start it, and no fuel came out! Since the truck had sat for so long, the fuel had turned to lacquer and coated the injector screens, restricting the fuel flow. I order a rebuild kit from Amazon and had it delivered the next day.

I pulled it off the intake manifold to rebuild it. I discovered that the screens on the injectors were coated and didnt allow any fuel to get out. It took a few minutes but I got them off and compared the new with the old, what a difference! I used carb cleaner and got them cleaned up pretty good. Replaced everything in the kit and reinstalled. Once again had my son turn on the key and low and behold a spray of fuel came out! Truck started right up after that.

I would check that to see if any fuel is coming out, then see about rebuilding it. You can also, purchase new injectors too.

The kit was like $20 or so. Best of luck




 
Johnnycam 
Newbie
Posts: 7

Reg: 06-24-20
07-04-20 09:21 PM - Post#2797924    
    In response to Chevytech

Hi everybody...I have ordered a new pump and will post an update! I appreciate all of the responses.



 
Johnnycam 
Newbie
Posts: 7

Reg: 06-24-20
07-08-20 04:38 PM - Post#2798237    
    In response to Johnnycam

Installed the new pump. Pumps fuel well. Connected the fuel line to the TBI...nothing. Checked all fuses and relay again. My thought is something is not supplying power to the injectors? Sprayers are completely dry when trying to start. Sent for a "NOID" light to test for pulse power at the injectors.
BTW...I retested the old pump...nothing, it was definitely dead. Thanks so much and keep the suggestions coming if you think of something I should check.



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3861
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
07-09-20 05:40 PM - Post#2798303    
    In response to Johnnycam

  • Johnnycam Said:
Installed the new pump. Pumps fuel well. Connected the fuel line to the TBI...nothing. Checked all fuses and relay again. My thought is something is not supplying power to the injectors? Sprayers are completely dry when trying to start. Sent for a "NOID" light to test for pulse power at the injectors.
BTW...I retested the old pump...nothing, it was definitely dead. Thanks so much and keep the suggestions coming if you think of something I should check.


With the key on there should always be power at the injectors. The ECM grounds the other side of the injectors, to make the injectors spray fuel.

I believe on your 1988 there is a shared wire for grounding the injectors. They are known to break where the two wires are spliced into one wire. The splice is close to the TBI unit in the harness.

The computer needs to receive a distributor reference pulse from the distributor module to trigger the injectors.

It is possible for the module to produce spark without the computer getting a reference pulse. A bad distributor module or wiring between the module and the ECM/PCM can cause this. If you had access to a scan tool you could see if there is a RPM signal when you crank the engine.

Many of the bigger auto parts stores in my area will test the distributor module for free if you bring it in.

Make sure when you install or reinstall the distributor module that you use heat sink compound under it. The compound helps dissipate heat from the module. Without it, the module will fail.

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
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