Help!! Car blows fuses. Can I use a slow blow fuse???

My '94 Bonneville has blown the fuse to the air pump for the air
shocks several dozen times over the last 8 years. Two dealers, a
different pump, and and $800 later it still blows fuses.
The only component on the fuse is the pump and the Chevy dealer
contends I need to try a third pump. I'm not convinced.
I wondered if trying a slow blow fuse (if they exist) might help. The
fuses I have been using are ATO 20A - small with square ended
terminals.
Anyone know if they make slowblow fuses like that and where to get
them???
I'm definitely about out of options.
At first we thought there might be a short somewhere, but never found
any. The mechanic even removed the dashboard to rewire and refuse the
components (I think he said 3) that were on the original circuit.
Now, the pump is on a circuit by itself. I have watched the pump run
and it sounds good. Seems to run about 10 seconds when it does run
and then shuts off without blowing the fuse. I can't tell exactly
when the fuse blows, but of course the ride soon suffers.
Any help would be GREATLY appreciated.
I have an appointment with ANOTHER mechanic in about 10 days, but hope
maybe to try a different type of fuse first.
Love the car otherwise, but this problem has been a big pain. There
MUST be an answer!!!

Bob Henninger

wizard2 wrote:
> My '94 Bonneville has blown the fuse to the air pump for the air
> shocks several dozen times over the last 8 years. Two dealers, a
> different pump, and and $800 later it still blows fuses.
> The only component on the fuse is the pump and the Chevy dealer
> contends I need to try a third pump. I'm not convinced.
> I wondered if trying a slow blow fuse (if they exist) might help. The
> fuses I have been using are ATO 20A - small with square ended
> terminals.
> Anyone know if they make slowblow fuses like that and where to get
> them???
> I'm definitely about out of options.
> At first we thought there might be a short somewhere, but never found
> any. The mechanic even removed the dashboard to rewire and refuse the
> components (I think he said 3) that were on the original circuit.
> Now, the pump is on a circuit by itself. I have watched the pump run
> and it sounds good. Seems to run about 10 seconds when it does run
> and then shuts off without blowing the fuse. I can't tell exactly
> when the fuse blows, but of course the ride soon suffers.
> Any help would be GREATLY appreciated.
> I have an appointment with ANOTHER mechanic in about 10 days, but hope
> maybe to try a different type of fuse first.
> Love the car otherwise, but this problem has been a big pain. There
> MUST be an answer!!!
>
> Bob Henninger

I don't know anything about your car or the amps required by the pump.
You should check the requirements of that pump. In any case, I don't
see what it would hurt to go with a bigger fuse. You have the circuit
isolated anyway. If it's a 15A fuse not it should take a 20A with no
bad consequences. Most serious shorts vasstly overpower the fuse anyway
so you will still be protected. If it were me I'd reach into my junk
box and pull out a resettable fuse at the required amperage and try
that until I had it figured out. For research purposes you could wire
in a test lamp and watch it on your dash for the event that precedes
the blowout. Since this has happened to more than one pump and the
circuit is newly wired, I suspect it's under fused.

In article >,
wizard2 > wrote:

> My '94 Bonneville has blown the fuse to the air pump for the air
> shocks several dozen times over the last 8 years. Two dealers, a
> different pump, and and $800 later it still blows fuses.
> The only component on the fuse is the pump and the Chevy dealer
> contends I need to try a third pump. I'm not convinced.
> I wondered if trying a slow blow fuse (if they exist) might help. The
> fuses I have been using are ATO 20A - small with square ended
> terminals.
> Anyone know if they make slowblow fuses like that and where to get
> them???
> I'm definitely about out of options.
> At first we thought there might be a short somewhere, but never found
> any. The mechanic even removed the dashboard to rewire and refuse the
> components (I think he said 3) that were on the original circuit.
> Now, the pump is on a circuit by itself. I have watched the pump run
> and it sounds good. Seems to run about 10 seconds when it does run
> and then shuts off without blowing the fuse. I can't tell exactly
> when the fuse blows, but of course the ride soon suffers.
> Any help would be GREATLY appreciated.
> I have an appointment with ANOTHER mechanic in about 10 days, but hope
> maybe to try a different type of fuse first.
> Love the car otherwise, but this problem has been a big pain. There
> MUST be an answer!!!
>
> Bob Henninger

Put an equal rating slo-blo in it and see what happens. The difficulty
may lie in finding one in the "blade" format - I'm really not sure if
there are slo-blo blade style fuses available, since I've never had a
reason to look for them. You may need to go to a fuse adapter rig so you
can replace the blade style with the tube style. Either way, if it's
blowing because the pump is overdrawing as it loads up, it'll likely
blow again, but should take slightly longer to do so, perhaps allowing
the pump to "finish" and shut itself off so things cool back to normal
before getting hot enough to actually fry the fuse.

Another thing I'd be looking at would be the cut-out switch, or any
controlling sensors that are involved with turning the pump on and off.
This on the suspicion that maybe the pump isn't being told to turn off,
and it can only handle pumping against <pick a number> PSI of
backpressure before overloading and blowing the fuse. Could indicate a
sensor that needs tweaking/replacing, a need for a new switch, or both.

If it's having to run so long/often that it cooks off fuses, it's also
possible that you've got something leaking in the system. If that's the
case, finding and fixing the leak would likely fix the fuse, albeit
indirectly.

--
Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

On Fri, 30 Sep 2005 15:59:10 -0400, wizard2 > wrote:

>My '94 Bonneville has blown the fuse to the air pump for the air
>shocks several dozen times over the last 8 years. ...
>At first we thought there might be a short somewhere, but never found
>any. ...

Not the same thing, but my Cavalier would intermittently blow its fuel
pump fuse. The Cav pump relay is on the inner fender, so the wire is
routed through the engine harness. The jacket on the harness was open
enough so that the wire in question rubbed on a bracket. The
insulation eventually wore through, and whenever the wire made contact
with the metal, poof.

Before I found that, I did try a larger fuse. It still blew, of
course. I think is would be perfectly safe for you to do that. But,
in the end, I think you'll find that it's a short.

Good luck,
George

i would be looking at the wires for a resistence and would bet the wire is getting
warm

Don Bruder wrote:

> In article >,
> wizard2 > wrote:
>
> > My '94 Bonneville has blown the fuse to the air pump for the air
> > shocks several dozen times over the last 8 years. Two dealers, a
> > different pump, and and $800 later it still blows fuses.
> > The only component on the fuse is the pump and the Chevy dealer
> > contends I need to try a third pump. I'm not convinced.
> > I wondered if trying a slow blow fuse (if they exist) might help. The
> > fuses I have been using are ATO 20A - small with square ended
> > terminals.
> > Anyone know if they make slowblow fuses like that and where to get
> > them???
> > I'm definitely about out of options.
> > At first we thought there might be a short somewhere, but never found
> > any. The mechanic even removed the dashboard to rewire and refuse the
> > components (I think he said 3) that were on the original circuit.
> > Now, the pump is on a circuit by itself. I have watched the pump run
> > and it sounds good. Seems to run about 10 seconds when it does run
> > and then shuts off without blowing the fuse. I can't tell exactly
> > when the fuse blows, but of course the ride soon suffers.
> > Any help would be GREATLY appreciated.
> > I have an appointment with ANOTHER mechanic in about 10 days, but hope
> > maybe to try a different type of fuse first.
> > Love the car otherwise, but this problem has been a big pain. There
> > MUST be an answer!!!
> >
> > Bob Henninger
>
> Put an equal rating slo-blo in it and see what happens. The difficulty
> may lie in finding one in the "blade" format - I'm really not sure if
> there are slo-blo blade style fuses available, since I've never had a
> reason to look for them. You may need to go to a fuse adapter rig so you
> can replace the blade style with the tube style. Either way, if it's
> blowing because the pump is overdrawing as it loads up, it'll likely
> blow again, but should take slightly longer to do so, perhaps allowing
> the pump to "finish" and shut itself off so things cool back to normal
> before getting hot enough to actually fry the fuse.
>
> Another thing I'd be looking at would be the cut-out switch, or any
> controlling sensors that are involved with turning the pump on and off.
> This on the suspicion that maybe the pump isn't being told to turn off,
> and it can only handle pumping against <pick a number> PSI of
> backpressure before overloading and blowing the fuse. Could indicate a
> sensor that needs tweaking/replacing, a need for a new switch, or both.
>
> If it's having to run so long/often that it cooks off fuses, it's also
> possible that you've got something leaking in the system. If that's the
> case, finding and fixing the leak would likely fix the fuse, albeit
> indirectly.
>
> --
> Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
> Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
> subject unless it comes from a "whitelisted" (pre-approved by me) address.
> See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

"wizard2" wrote

> I wondered if trying a slow blow fuse (if they exist) might help. The
> fuses I have been using are ATO 20A - small with square ended
> terminals.
> Anyone know if they make slowblow fuses like that and where to get
> them???

How about a circuit breaker that plugs into the same ATO slot?
Wrecking yard cars are full of them. Go grab a pocketful.

How much does a new air pump cost, and how hard is it to install
compared to a fuse?

I'd measure the current draw and the voltage at the pump's terminals
since electric pumps often draw more current than normal when the pump
mechanism wears or when the motor doesn't receive full voltage. Be
sure to measure the voltage at the pump's terminals, not the terminals
of the connector that plugs into them.
Compare this to the voltage at the battery terminals; it should be
within 1/2 V.

While you're at it, unplug and clean all the connections (don't sand
them -- can remove protective plating), pry
any press-on terminals so they grip better, and coat terminals with
silicone grease (Radio Shack's transistor heatsink grease, automotive
dielectric grease, or computer CPU heatsink grease, provided the latter
doesn't contain silver). Apply the grease before reassembly so it
seals out water better. The grease will not impede flow of current
since the metal pierces its film.

If for some strange reason GM uses the chassis as the negative
connection for the pump, clean that connection too, and consider
running an extra ground wire (#10-12 is fine).

Thanks very much to all of you for your great ideas! I haven't had a
chance yet to try any of them myself. The car goes into the shop this
afternoon. I will print all of your responses and give them to the
mechanic. Will post the final outcome here, hopefully later this
week.
BTW, just returned from a 400 mile trip with no blown fuses. Sheesh.
Thank you again for taking the time to help.
Bob Henninger

On Fri, 30 Sep 2005 15:59:10 -0400, wizard2 > wrote:

>My '94 Bonneville has blown the fuse to the air pump for the air
>shocks several dozen times over the last 8 years. Two dealers, a
>different pump, and and $800 later it still blows fuses.
>The only component on the fuse is the pump and the Chevy dealer
>contends I need to try a third pump. I'm not convinced.
>I wondered if trying a slow blow fuse (if they exist) might help. The
>fuses I have been using are ATO 20A - small with square ended
>terminals.
>Anyone know if they make slowblow fuses like that and where to get
>them???
>I'm definitely about out of options.
>At first we thought there might be a short somewhere, but never found
>any. The mechanic even removed the dashboard to rewire and refuse the
>components (I think he said 3) that were on the original circuit.
>Now, the pump is on a circuit by itself. I have watched the pump run
>and it sounds good. Seems to run about 10 seconds when it does run
>and then shuts off without blowing the fuse. I can't tell exactly
>when the fuse blows, but of course the ride soon suffers.
>Any help would be GREATLY appreciated.
>I have an appointment with ANOTHER mechanic in about 10 days, but hope
>maybe to try a different type of fuse first.
>Love the car otherwise, but this problem has been a big pain. There
>MUST be an answer!!!
>
>Bob Henninger

Have you installed an ammeter across the fuse plug and actually viewed the
amperage drawn?

On my old Saturn one circuit had the electric window motors in the same
circuit as some the wipers (?). If the wipers were on and I happened to hit
a window switch the fuse would blow. Turns out there was a memo to the
dealer that the fuse value was too low for that circuit. It was doubled, as
I recall, and all blown fuse problems went away. The ammeter showed the
circuit as just about maxed, but when the wiper washer was activated it went
over. Slow-Blo fuse didn't matter much. It was too low to begin with if
all accessories were switched on in that circuit.

Mack

On Tue, 11 Oct 2005 13:17:17 -0700, M. MacDonald > wrote:


>Have you installed an ammeter across the fuse plug and actually viewed the
>amperage drawn?

>On my old Saturn one circuit had the electric window motors in the same
>circuit as some the wipers (?). If the wipers were on and I happened to hit
>a window switch the fuse would blow. Turns out there was a memo to the
>dealer that the fuse value was too low for that circuit. It was doubled, as
>I recall, and all blown fuse problems went away. The ammeter showed the
>circuit as just about maxed, but when the wiper washer was activated it went
>over. Slow-Blo fuse didn't matter much. It was too low to begin with if
>all accessories were switched on in that circuit.

Slow-blo fuses aren't that slow. Using such a fuse would only matter if you
were somehow able to finish raising your windows in under a half second.