Cranks but won't start

Mooseman

Moderator
'05+ have the filter on the pump.
 

coolride

Silver Supporter
I've seen pictures of pumps with filters that hang off the bottom, and also filters inside the pump assembly "cans." By "can" I mean that plastic canister that holds gas when the pump is removed.
 

Mooseman

Moderator
I think those are the old type with the sock on the bottom. The newer ones have the filter inside that canister.
 

coolride

Silver Supporter
I think those are the old type with the sock on the bottom. The newer ones have the filter inside that canister.

I pulled the pump and see a filter inside the canister.👍

When I pulled the pump I noticed the O-ring was inside the tank (wrapped around the body of the pump assembly.) I don't know if the O-ring fell during pump installation, or during removal.

I attempted to reinstall the pump with the O-ring in place and now the lock ring won't engage the tabs. Is this a common problem?

It's a Bosch pump with a green O-ring.
 
Last edited:

coolride

Silver Supporter
Here's a look at the tank flange. It's just tank material (apparently some type of laminate.) There's no "sleeve" type OEM O-ring.

fuelpump5.jpg
 
Last edited:

Mooseman

Moderator
There should be a channel all around for the o-ring to sit in. Check inside the tank for a piece of plastic or metal that may have fallen in.
 

coolride

Silver Supporter
Yeah, there's a channel for the o-ring. The problem is, the o-ring is so thick that I can't get the lock ring started.

Next attempt I'll lube the o-ring with silicone grease. Maybe that will help it to spread and flatten out enough to get the lock ring down.
 

NJTB

Silver Supporter
That happend to me, too. Wound up buying the J tool (sorry, don't remember the PN) and installed it that way. I do remember there's about 3 for the TB, look it up for your year.
 

coolride

Silver Supporter
Testing the fuel pump harness. With the key on I'm getting 4.9 volts between the grey and the green. Is this correct?

fuelpump6.jpg
 
Last edited:

Mooseman

Moderator
Is that for the fuel pump? It should have 4 wires. That's probably for the tank pressure sensor. In that case, you should have 5v between black (-) and gray (5v ref). Green is the sensor output.

On the pump plug, it's:
Gray: 12v+
Blk: ground
ppl and orn/blk: level sender output
 

coolride

Silver Supporter
Thank you. Just tested again.

I see 12v when key is on but it quickly backs off to zero. So temporarily,,,there is 12V. During cranking I see 10V.
 

coolride

Silver Supporter
Ran test again, but used a lead to the neg. battery terminal for the ground (reliable ground.)

Same results. Saw battery voltage with the key on, but only momentarily, then voltage dropped to zero.

While cranking it had 10V.
 
Last edited:

Mooseman

Moderator
That is normal. When in RUN, the PCM primes the pump for just a couple of seconds and switches off the relay until you turn the key to START and stays running. Instead on a meter, use something that draws some amps, like a headlight bulb, to see if enough amps go through the wiring. It can happen that you can see a no load voltage but drops off with an actual load. When plugged in, do you hear the pump run while it's priming?

That's pretty low voltage while cranking. Is the battery good?
 

coolride

Silver Supporter
The battery has been sitting for a looong time. So it's a little weak. I'll get it onto a charger tonight. The pump is out of the tank and in a different room but back when it was installed yes, I could hear it prime.

If there's low amps under load, what's the busted component?
 
Last edited:

Mooseman

Moderator
Could be the relay, wiring, connector or fuse contact. They've been known to get loose and/or corrode.
 

coolride

Silver Supporter
I tested both fuel level sensors. The new one (background) is whacked. The ohm readings are all over the place. No wonder my fuel gauge wasn't working right. The old one works fine.fuelpump7.jpg
 
Last edited:

coolride

Silver Supporter
Looking at the Bosch paper work now, and wondering how to get a refund from Amazon. I want a better pump. Called Newparts Inc. of Gordonsville, TN (the seller) and left a voicemail. Was told to expect an email reply.
 
Last edited:

coolride

Silver Supporter
For load testing the circuit, I have a bulb wired up as the load. I can do a high beam test, and a low beam test. (now what?)

loadtest2.jpg


loadtest1.jpg
 

coolride

Silver Supporter
Does the load test have to be done with the pump installed? The problem I'm seeing is that the PCM cuts power to the pump after a moment with the key on. Hard to test like that.
 

Mooseman

Moderator
Unfortunately, that's how the PCM works. What you could do is pull the starter relay and turn the key to CRANK. It will command the fuel pump on while cranking.
 

coolride

Silver Supporter
Rigged up a load with the stuff I could find (nails, alligator clips, wire, and scrap wood.) It works, but doesn't look great. This is a low beam load.

fuelpump9.jpg


fuelpump11.jpg


fuelpump12.jpg
 
Last edited:

coolride

Silver Supporter
Load testing completed. I am reading 0.1v negative side and 0.3v positive side. So no problems are obvious. I'm thinking next; get the pump installed and hook up the tank. I'll repeat the load test with the tank connected, but not strapped up.
fuelpump19.jpg
 
Last edited:

coolride

Silver Supporter
Spoke to Bosch:

Don't buy a Bosch fuel pump (or anything) from a non-approved Online Partner. This seller is offering auto parts on Amazon.

Newparts Inc. 231 Hogan Rd. Gordonville, TN 38563

NOT an approved online partner. Bosch said they are probably re-selling returned or damaged items.
 
Last edited:

NJTB

Silver Supporter
@coolride
Amazing, isn't it. Back in the day, GM had a problem with distributor caps. They were scrapping defective ones, but they kept turning up, then were returned to the store again.
Turns out someone was pulling the caps out of the trash and re selling them.
 

Online statistics

Members online
6
Guests online
319
Total visitors
325

Members online

Forum statistics

Threads
21,282
Messages
609,480
Members
15,045
Latest member
LuckyLuce

Secure Browsing

Top Bottom