Okay I'm truly stumped on this one. And with only 9 days till race day the truck is blocking the driveway and I am unable to get the car out for the next rallycross.
It is an 87 suburban 350 SBC TBI
I cleaned the grounds on the alt bracket, core support, behind dash just to be sure.
I am getting power to the starter
I am getting B+ at the ignition switch but I have .9v in the accy and run position.
I can sometimes hear the fuel pump turn on and prime.
I have no blown fuses.
I thought it would have been an ignition switch issue so I replaced it and nothing.
I'm stumped...
No crank or no fire? If you can jump the started solenoid and it doesn't turn over, then the starter is toast. Have you had the battery tested? Just because it shows a surface charge doesn't mean it's got cranking power.
Does it crank over but not fire?
No crank?
The fuel pump will only turn on when the pressure is down.
Bobzilla wrote:
No crank or no fire? If you can jump the started solenoid and it doesn't turn over, then the starter is toast. Have you had the battery tested? Just because it shows a surface charge doesn't mean it's got cranking power.
no crank and no fire, no power in the accy/run position, IE power windows and horn stopped working.
Battery is less than 6 months old, headlamps turn on fine. I've got 12v at the alternator and the junction block.
Yeah, try jumping the starter. Sounds like you checked everything else.
The starter on those things is pretty easy to get to and pull (2 bolts- but be prepared to catch it and it weighs a lot!)- it sounds like it's a good place to start. Pull it, make note of where the wires to it connect, and take it to your local AutoZone/etc. and have them test it. If it fails, you're already there at the parts store to get a new one.
Pull the battery and take it with you while you do this and have them do a full check on it- cranking over a 350 takes a good bit more juice than just lighting up the headlights...
Spinout007 wrote:
Yeah, try jumping the starter. Sounds like you checked everything else.
But that doesn't explain the loss of power to my ign and accy
bad grounds or a bad battery. I've seen my fair share of batteries that show 12.5V but as soon as you put a load on them they go flat, take the load off and they jump back to 12.xV again.
Ranger50 wrote:
Sounds like no grounds.
and the starter grounds through the block. I'm going to try and jump the starter when I get back from work later but I'm not having high hopes. I think last time when I checked across the terminals I was only getting 10.6v
Put your multimeter across the battery terminals and see if when you turn the key to crank if the number goes below 9-10V. If it does go below, bad battery, IME. If it doesn't move, ignition switch related.
fidelity101 wrote:
Ranger50 wrote:
Sounds like no grounds.
and the starter grounds through the block. I'm going to try and jump the starter when I get back from work later but I'm not having high hopes. I think last time when I checked across the terminals I was only getting 10.6v
no load on the battery 10.6v? if so bad cell in battery.
Ranger50 wrote:
fidelity101 wrote:
Ranger50 wrote:
Sounds like no grounds.
and the starter grounds through the block. I'm going to try and jump the starter when I get back from work later but I'm not having high hopes. I think last time when I checked across the terminals I was only getting 10.6v
no load on the battery 10.6v? if so bad cell in battery.
but then how would ignition switch and junction block get 12.2v, I swapped the ignition switch already and no change, 12v going in for constant power and less than 1v coming out for accy/run position.
Sounds like its time to find a wiring diagram.
Are you sure that there is only 1 wire suppling voltage into the ignition switch? Its not unheard of to have more than one circuit going through an ignition switch.
Also check the condition of the wires and connector pins/sockets where the harness plugs into the switch.
Check for fusible links, GM loves them, one could be burnt out, and still show battery voltage when not under a load.
In reply to HappyAndy:
I should re-phrase. both B+ connections show 12.2v at the switch and the connectors look good, unlike my headlamp connectors, those are almost green! I'll have to check the fuseable links(wherever they may be) I have a Chilton manual and some GM wiring schematics printed out for the fuse box/ign switch.
since everyone has worked on the starting issues, i'd like to take this post to point out that there never was a "K5 Suburban". .the only "K5" in the GM lineup in the 80's was the 2 door K5 Blazer- which was the original full size version of the Blazer that only got the "K5" name to avoid confusion in the 80's when the smaller S series Blazers came out.
a Suburban was just a "Suburban" and had 4 doors and was about 4 feet longer than a K5 Blazer.
Had a rx7 once that when you tried to crank it, it would kill just about everything else. Replaced the starter and wa la, everything was as it should. But I will say that was with a known good battery.
Ranger50 wrote:
Put your multimeter across the battery terminals and see if when you turn the key to crank if the number goes below 9-10V. If it does go below, bad battery, IME. If it doesn't move, ignition switch related.
Okay, i doubled checked my readings:
12.3v at starter, and no change in voltage during crank. I tried jumping across the two pins on the starter with a wire and i managed to get a brief contact/spark but that was it
Sounds like you need a starter, battery, or both.
I owned a chevy van of similar vintage and had to replace the starter twice in 100k miles. Luckily its really really easy to get to, 5 minute job.
fidelity101 wrote:
Ranger50 wrote:
Put your multimeter across the battery terminals and see if when you turn the key to crank if the number goes below 9-10V. If it does go below, bad battery, IME. If it doesn't move, ignition switch related.
Okay, i doubled checked my readings:
12.3v at starter, and no change in voltage during crank. I tried jumping across the two pins on the starter with a wire and i managed to get a brief contact/spark but that was it
Are you getting that reading at the power cable or the solenoid when the switch is being turned. You should see 12+ at the big starter cable all the time. You should see 12+ volts at the little solenoid wire only when the key is held in the start position. If you are getting 12 volts at the solenoid and it isnt kicking on you have a bad starter. If you are not getting 12+ volts to the solenoid you need to look upstream.
That piece of information will be very helpful in figuring this out.
In reply to logdog:
Yes I am reading B+ at the starter at all time. I removed the started and had it tested and it checked out good pulled 97 amps and a new one tested at 104. The motor sounded pretty bad so I just bought a new one for 40 dollars, couldn't resist for that price lol.
Still with B+ going to the ignition switch and nothing coming out it must be the switch, going to return the new one for a DOA, re-install both and see.
Really not looking forward to having to tear the whole wiring harness apart...
I assume you have checked that you can turn over the motor by hand?
Does it have a clutch safety switch? Not likely the problem but I don't have any other ideas.
EvanB wrote:
Does it have a clutch safety switch? Not likely the problem but I don't have any other ideas.
yes and I've even jumped it to avoid pressing the clutch for diag in this situation.
I have not checked to see if I can turn the motor by hand because I'm having more of an electrical issue, if I could hear the starter click every time I used the key and the engine wouldn't crank I'd give that a shot, but i did check the oil level and its not filled with coolant and very high so i'm doubting its a mechanical related failure.
