Is it the Fuel Pump? (Just drove her, no parts necessary!) - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1987-1991 Parley with regards to your 1987 to 1991 Bonneville, Olds 88 or Buick Le Sabre Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Reply
 
 
 
Thread Tools Search this Thread
Old 07-15-2007, 07:18 PM   #1
Senior Member
Posts like a Camaro
Thread Starter
 
Join Date: Jan 2003
Location: Jenison, MI (Near Grand Rapids)
Posts: 1,070
Thanks: 0
Thanked 0 Times in 0 Posts
theJMFC is on a distinguished road
Default Is it the Fuel Pump? (Just drove her, no parts necessary!)

First of all, the answer I really want is, "no, it'* something far cheaper." So please keep that in mind as we move on.

The '89 has been running a little bit "off" for the past few weeks, mostly when cold. It has a hesitation from one certain stop sign on my way home from work, after driving about 1/4 mile. Otherwise, when warm, it runs pretty good.

Just the past few days, it'* not wanted to start. It'* never been an instant starter, by any means, but then one day, it cranked, sputtered to life, and died. Then it cranked and cranked with no luck. Finally, just before throwing in the towel and taking the wife'* car to work, I tried cranking it for just a couple seconds, released the key, and it chugged to life. Ran fine all the way to work and back home that evening.

Since then, I've noticed that it'll crank all day long, but until I let go of the key, it won't fire up. Usually it will fire up after a couple/three tries of this method (crank for a couple seconds, release key, repeat as necessary).

But since it seemed to only be getting worse, I started trouble-shooting. My first thought was ignition, since maybe the spark was weak while there was current going to the starter. So, I checked the gap on the plugs (it was a little big), swapped in another set of wires (old and new ones checked out with a multimeter) , swapped the coils and ICM for known good ones off of the LeSabre, all to no avail. I ran it between all steps, too, and nothing changed.

So just for kicks, I threw on my trusty fuel pressure gauge and turned on the key. It registered like 5 psi. After a few cycles of the key, it made it up to about 21 psi. No higher. It did hold there, no leaks. Even after cranking (it wasn't in a starting mood at this point), it stayed at only about 21-22 psi. Of course, the specs for this are somewhere over 40 psi...

My first thought is obviously the fuel pump. But could it be anything else?

I thought maybe the filter, but it runs and revs fine once it starts (when it starts), so i have volume, just not pressure.

My other hope is the fuel pressure regulator. There'* no fuel in the vacuum line. Beyond that, I'm unsure how to test those, short of swapping in another. I have my doubts though, since it takes a couple of key turns to even get the pressure to 21 psi.

Any thoughts? Any hope at all that it'* not my pump? If it is, I'll have to do some hard thinking before going to the trouble and expense of replacing it. It'* got some Michigan rust in all the wrong/vital places, and I'm not sure how much money I'm willing to put into it anymore, as much as I love this car.
theJMFC is offline   Reply With Quote
Old 07-15-2007, 08:28 PM   #2
BANNED
 
Join Date: Aug 2002
Posts: 0
Thanks: 0
Thanked 0 Times in 0 Posts
banned3800 is on a distinguished road
Default

The car should see 37-41 PSI, in most cases I have seen them a little higher than that... But that is the range..

It would seem like a Clogged fuel filter or bad fuel pump...The FPR is also suspect.... I'd look for one on a Yard car to test with..

I'm on the thought of Fuel pump tho

__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
banned3800 is offline   Reply With Quote
Old 07-15-2007, 08:39 PM   #3
Senior Member
Posts like a Camaro
Thread Starter
 
Join Date: Jan 2003
Location: Jenison, MI (Near Grand Rapids)
Posts: 1,070
Thanks: 0
Thanked 0 Times in 0 Posts
theJMFC is on a distinguished road
Default

Thanks for the speedy reply man. It'* Don, right? It'* been a while... real life keeping me busy and all...

I might know a guy with a FPR (whole car, actually) that he'* not using at the moment. I'll have to talk to him about borrowing it for a while.

I actually bought a new fuel filter for it a few years back. Then I looked at the connections on the old one, and thought better of fixing what wasn't necessarily broken. I doubt they look much better after a few more winters. I still say that since it seems to be a lack of pressure, not volume, that the filter is probably alright...

I'll try to track down that FPR though, and see if I get lucky.

Of course, meanwhile, other opinions are welcome.
theJMFC is offline   Reply With Quote
Old 07-15-2007, 11:31 PM   #4
Senior Member
Posts like a Camaro
Thread Starter
 
Join Date: Jan 2003
Location: Jenison, MI (Near Grand Rapids)
Posts: 1,070
Thanks: 0
Thanked 0 Times in 0 Posts
theJMFC is on a distinguished road
Default

Back on the topic of the FPR: can those be tested somehow? Obviously if the car had rubber fuel return line, I could just try pinching it off to see if the regulator is allowing pressure to escape, but it'* steel. And I can't think of any other way of testing it...

I can't get my hands on another to swap in for a couple days, thus the testing question.

That said, it'* probably still the stupid pump. In which case, I'll probably try my hand at dropping the tank and loosening fittings that haven't been loosened in 18 years, and have lived their lives over the salty winter roads of Michigan. Woohoo!

But I really hope it'* just a FPR. Any suggestions on the testing one of those?
theJMFC is offline   Reply With Quote
Old 07-16-2007, 03:57 PM   #5
Senior Member
Posts like a Camaro
Thread Starter
 
Join Date: Jan 2003
Location: Jenison, MI (Near Grand Rapids)
Posts: 1,070
Thanks: 0
Thanked 0 Times in 0 Posts
theJMFC is on a distinguished road
Default

Nevermind on the FPR test question. I just plugged the return fitting, and it made no difference. So the FPR isn't the weak link.

I also found the fuel pump test/prime lead by the battery. Putting 12v to that was the same as turning the key on, pressure wise, so that makes the relay good.

So that leaves the wiring from the relay to the pump, or the pump itself. Or a ground, I suppose.

One thing I did notice that seemed kinda wrong was that a few times while I cycled the ignition switch to run, I could hear a relay under the dash clicking on and off every few seconds, seemingly at random. Dropping the glove box, I can see two relays and three fuses, so I guess it'* one of those relays turning itself on and off. So I have to wonder if maybe I have a weak ground up in there? I do have a lot of rust in that area, where the windshield, door, and fender all come together. Any thoughts on that? Or better yet, anyone know where exactly that ground is located, or if it even has one?

Of course, even when the relay did stay on, the pressure remained at about 20-22, so unless the pump and the relay share a ground point, it'* a separate issue.

It'* raining right now, and I have to go to work. I'll have to see what you guys say and do some more digging tomorrow.
theJMFC is offline   Reply With Quote
Old 07-16-2007, 07:09 PM   #6
Senior Member
Posts like a Turbo
 
Join Date: Jul 2007
Location: Joplin, Missouri
Posts: 354
Thanks: 0
Thanked 0 Times in 0 Posts
Alibi is on a distinguished road
Default

I could be the relay, but I really doubt it. The FP relay should be on the right side, I think its the third one down. Maybe the second one down but I think thats for the horn.

I vote faulty fuel pump. A new one can be had for around $100 at Autozone... However, if I were you I'd go ahead and try to get the filter swapped out... the only last 15k miles so they do eventually clog up. Besides, they're like $10... just be sure to use line wrenches or you risk stripping the nuts.
Alibi is offline   Reply With Quote
Old 07-17-2007, 02:37 AM   #7
Senior Member
Posts like a Camaro
Thread Starter
 
Join Date: Jan 2003
Location: Jenison, MI (Near Grand Rapids)
Posts: 1,070
Thanks: 0
Thanked 0 Times in 0 Posts
theJMFC is on a distinguished road
Default

I think that tomorrow I'll see if maybe I can convince it to run once more, so that I can drive it back up on ramps. I could really use the headroom to check voltages at the connector back there, not to mention dropping the tank, if it comes to that.

yeah, I'll be tempted to change out the filter if I'm doing the pump anyway. I'm 90% sure it'* not the actual problem though, since I have flow (car will run fine if it will start), but not good pressure even when there is no flow (key on, engine not running).

The relay, I'm convinced, is not the problem, since I get the same pressure result when I jumper the test/prime wire to the battery (effectively bypassing the relay). So it might be flaky, but it'* not why I'm dead in the driveway.
theJMFC is offline   Reply With Quote
Old 07-17-2007, 04:11 PM   #8
Senior Member
Posts like a Camaro
Thread Starter
 
Join Date: Jan 2003
Location: Jenison, MI (Near Grand Rapids)
Posts: 1,070
Thanks: 0
Thanked 0 Times in 0 Posts
theJMFC is on a distinguished road
Default

Well, did some more poking and prodding today. I get a 12v difference between the fuel pump power and ground as far back as where the wires pass through the trunk, just before passing down to the tank (with the test/prime lead given 12v). And the connector down there looks nice and clean, corrosion-free. That pretty much leaves the pump, am I right?

Oh, I did also check the ground busses near the front door area. Despite that area being wet just from the rust holes and a light overnight rain, those are fine.

Despite managing to get pressure up to around 30 psi by touching the test/prime lead with 12v for about a second at a time, many times in a row, the thing would not start. So I got it up on jack stands so that I could crawl under there and take a look at how evil it'* going to be to get at. The straps look decent. Even if I had to drill them out, there is access to replace the stock bolts and clips with new. The fuel fittings are very crusty, and I'm not looking forward to those one bit.

The underside of the car has made me wonder once again if it'* worth throwing any money into at all. Soooo rusty, and in all the wrong places. Still, unless I find something else... I'* got to get to work.
theJMFC is offline   Reply With Quote
Old 07-17-2007, 07:34 PM   #9
Senior Member
Posts like a Turbo
 
Join Date: Mar 2002
Location: Philly
Posts: 297
Thanks: 0
Thanked 0 Times in 0 Posts
KEOTOK is on a distinguished road
Default

I was thinking a break in the lines somewhere, but I dont think that the pressure would hold, and you'd see a leak.

How about the fuel cap? Swap it out if you have a another car.

I'm leaning towards pump.
KEOTOK is offline   Reply With Quote
Old 07-18-2007, 02:27 AM   #10
Senior Member
Posts like a Camaro
Thread Starter
 
Join Date: Jan 2003
Location: Jenison, MI (Near Grand Rapids)
Posts: 1,070
Thanks: 0
Thanked 0 Times in 0 Posts
theJMFC is on a distinguished road
Default

Yeah, I won't say the lines are good... but no leaks that I can see on dry pavement, or smell. And it does seem to hold it'* 20 psi for a while key-off (not forever though, must be a slowly leaking regulator or something).

I actually just thought of the gas cap today as I was leaving for work, and I just opened it up to see if I would hear a hiss of vacuum or anything. All was quiet and seemed normal. So, I doubt that'* it either.

As much as I hate to admit it, at this point, it'* really got to be the pump.

Only question left then is, "is it worth it?"

I figure sure, it'* probably worth the $100 or so I'll end up paying for a new pump and strainer. But what if 18-year-old fuel lines start breaking off in my hands? Then I might well be looking at a new sending unit ($150 at AutoZone), some new fuel lines, etc. I figure the car to be worth around $500-600 in running condition. So a fuel pump and strainer would be about 20% of the car'* value. I'm willing to do that. But add in some extra, unforeseen costs, and I could be looking at more like 50% of it'* value. Not sure I can justify that...

But hey, I guess I can see what comes loose without spending any money, right? Right.

So, since the bugger won't start up now, I'm going to probably resort to using a winch and a handy maple tree to pull it backwards up onto some ramps, and go from there.
theJMFC is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Are Z-rated tires necessary? radomirthegreat General GM Chat 15 12-09-2007 03:06 PM
Is premium gas necessary for a supercharged 3.8? ohio67 General GM Chat 9 11-01-2007 12:33 AM
GXP"S Next Mod Plan Of Attack.....And other necessary B GXP Venom General GM Chat 9 04-09-2006 11:17 AM
BALL JOINTS AND HUB IS A ALIGNMENT NECESSARY? Kennginn 1992-1999 6 02-29-2004 12:03 PM
is Air Ride Leveling system necessary or just fancy option mhodgson 1987-1991 11 12-30-2003 12:23 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 01:27 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.