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Username Post: 95 C1500 cranks but no start        (Topic#361231)
93 low 
Poster
Posts: 77

Loc: So Cal
Reg: 12-06-11
06-01-20 09:38 PM - Post#2795445    

95 C1500 5.7 TBI Silverado. Truck sat for about 6 weeks. Engine cranks but no start, dash gauge shows less than 9 volts (volts at batt 12.22) I charge the batt overnight and try it again. Same thing, engine cranks but no start, I tried to jump start it and no change (dash gauge still shows less than 9 volts, batt 13.73 volts) I checked the fuses under the hood, fuses good and had batt voltage to all fuses except to the ECM 1 fuse (20 amp). No power to the ECM 1 with or without the key on.

Should the ECM 1 fuse block have power to it?

Thanks



 
CowboyTrukr 
"9th Year" Silver Supporting Member
Posts: 4436
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
06-01-20 10:49 PM - Post#2795446    
    In response to 93 low

Yes. ECM1 Fuse is the one that powers the fuel pump. There is only one reason why that fuse has blown. There is a problem with the power feed back to the fuel pump. Two possible culprits: Shorted wiring back on top of the fuel tank, or in the vicinity, or a problem with your oil pressure sending unit. Mine had a defective oil pressure switch. The oil pressure switch is designed to be a supplemental power feed to the truck if you happen to have a problem with the fuel pump relay.

It is supposed to close in, providing power to the fuel pump, when the engine oil pressure gets up to about 15psi.

Mine would actually fire and then immediately die. The oil switch was shorted internally to the switch body, blowing the fuse the infant the pressure was high enough.

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


 
93 low 
Poster
Posts: 77

Loc: So Cal
Reg: 12-06-11
06-02-20 09:54 AM - Post#2795468    
    In response to CowboyTrukr

Cowboy, Thanks for your response. The ECM 1 fuse did not blow, just no power to the fuse block.

Can I bring power to the fuse block and check if it would start or would that cause another problem?

Where is the oil switch located?

Is the oil pressure sending unit and oil pressure switch the same thing?

Thanks




Edited by 93 low on 06-02-20 10:13 AM. Reason for edit: No reason given.

 
someotherguy 
Senior Moderator
Posts: 29180
someotherguy
Age: 50
Loc: Texas
Reg: 08-01-03
06-02-20 10:42 AM - Post#2795471    
    In response to 93 low

  • 93 low Said:
Where is the oil switch located?

Is the oil pressure sending unit and oil pressure switch the same thing?


It's at the top rear of the block below the lifter valley "rail" - underneath the distributor, a bit difficult to see. Yes, on a '95 model the sending unit and pressure switch are combined into the same part. (The first few years of these trucks had separate components for these functions.)

You could attempt jumping the fuel pump at the diagnostic connector under the dash. If you jumper A and G it should operate the fuel pump IF the fuel pump relay and fuse are good. A and G are the top right pin and bottom left pin on the connector.

If those don't get it done, you should be able to find a 2 pin connector on the driver's side firewall (engine compartment side, not interior) below the brake booster area, running towards the frame rail - that will be for the fuel pump and you can supply +12V and GND to it to power the pump. Polarity matters so if you don't get it right the first time just flip it. Sometimes...the pump ground near the fuel tank can become damaged, so don't overlook it.

The '95 model year is a bit notorious for issues with the ignition switch and that may be what you're facing with lack of power to that circuit although the fuse is good. Do be sure though that you're testing the fuse with an ohmmeter set on continuity and not just eyeballing it.

Richard

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


 
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