Keep blowing fuel pump fuse... wit's end...

[veedubcrazy]

First off, the car is a '87 Buick T-Type, stock for the most part. Where I am having the problem is the fuel pump fuses keep blowing after installing Casper Elec. fuel pump relay. The TR does have an additional fuel pump (rotary) in addition to the fuel pump in the tank. The pump in the tank has been replaced a few month back when the tank got dipped and pinholes welded up. The TR ran fine without the fuel pump relay but I wanted to replace what had been ripped out prior.

Do I need to remove the rotary and just use the pump in the tank? Is it drawing too much amperage thru the circuit? It did blow a 30A fuse in the fuse block. It did have a 15A in originally.

I mean, whats the deal? Am I alone in this? Please help...

Dave

 

[veedubcrazy]

Here is a picture of the rotary fuel pump under the T-Type. The PO is my father-in-law but in his defense, thats how he bought the car.

I am just trying to get this right...

 

[Chuck Leeper]

I'd trash that ext pump. It has corroded wiring connectors, and a kinked fuel inlet line.[SCARY!]
If the intank is a good pump, it will be more than enuf to run that engine combo.

while U R at it, I'd take a good look at the frame, near the pump.. Is that a crack I see?

 

[dr_frankenstein]

oh my, that needs to go.

A.j.

 

[veedubcrazy]

Yes, there is a crack in the LCA forward bolt mount. I have new LCA's coming from HRpartsNstuf and I will address both cracks in the mounts. But there are none anywhere else. I cannot tell you how much I appreciate all the help here.

As far as the pump goes, I will remove it ASAP. I will also have to order a new steel fuel line from the filter back to the tank. Yes, there is a kink in the line and I am going to take care of that. The pix I have taken are points of interest I have to take care of. And I figure putting them here helps with the problem.

I am in the process of getting the T-Type back on the road after sitting in the garage for 4-5 years.

 

[veedubcrazy]

Update here...

Snipped and removed all the wires running to the ext. fuel pump and verified that tank pump is running. Ext. pump still in for now but will be removed when I get a chance. Fuse still blows when key is turned on prior to starting. I am thinking that somehow the new F.P. relay may be wired wrong but the wires to it color match. I did find a wiring diagram here so I will see what is going on. Thanx...

 

[BlackBandit]

As far as the fuel pump fuse blowing goes check to make sure there are no wires touching your drivers side header. If you have a hot wire setup then there should be virtually no load on your stock fuel pump circuit.

Also, I would look into doing braided aircraft line from the tank to the fuel pump. You'll save yourself allot of headache.

 

[Ttype6]

The oil pressure switch is in the fuel pump cicuit. Can create a short circuit. Common. Unplug it to test it. If fuse doesn't blow, pressure switch is bad. I would use that pump'but I wouldn't have it run all the time. It's noisy and you would just be heating the fuel. Also,the fuel return line is too small to return the large folume of fuel it moves at low engine demands of low rpm or low boost. The higher demands of fuel when the engine is reving higher and making boost results in more fuel passing through the injectors and into the motor and less fuel being returned to the tank. The fuel retun line is big enough in this situation. To accomplish what you want you'll want your external pump to be turned on by another relay that is activated by a pressure switch recieving its pressure signal from the line going to the map sensor or boost guage. A good pressure switch to use is an oil pressure switch from an 86 or 87 Ttype or GN. This switch will turn you pump on at 11 psi. If it turns out that your pressure switch is good,you can disconnect the negative wire to the external pump to see if your fuse still blows. The intank pump will push fuel through the external pump. If you have a fuel pressure guage you will see the idle pressure drop when you disconnect the power to the exteral pump. This is because the return line is big enough to return the lesser volumn of unused fuel. Your external pump is the Bosch pump that Jim bell of Kenne-Bell used to market,and is the same pump I still use. It,s good insurance to have the capability to move a much greater volume of fuel than you need so when your intank pump gets tired(before you notice it) your external pump will save you from a blown head gasket or worse.

 

[DR BOOST]

i believe your fuel injector harness runs off the same fuse as the pump. make sure you have no burned/ broken wires in the fuel pump harness

 

[veedubcrazy]

Update... Isolate the ext pump and still blows fuse. Removed oil press sensor and car ran till died. But it did not blow the fuse. Reconnected the sensor and unplugged the fuel pump relay and TR started up. I can hear the pump run in the tank. I disconnected the black wire to the relay and fuse remained intact. Hmmm.... Anyway, I wrapped it up for the night but I did see a melted wire loom under the pass side exh. header. Did not investigate as it is too late. I will look at it tomorrow...

 

[Chuck Leeper]

" I did see a melted wire loom under the pass side exh. header."
Sounds like you are on the right track.

 

[veedubcrazy]

" I did see a melted wire loom under the pass side exh. header."
Sounds like you are on the right track.

Yes, I will look into that tonite. It was too late to go further on it but at least I saw something that needs attention. That and I am going to order a new oil press switch as well as new V.C. gaskets. They are seeping oil onto the header and makes a bit of smoke...

No one said getting to the oil press switch was going to be easy...:wink:

 

[veedubcrazy]

Called a buddy of mine that works the parts counter at a local Chevy dealership and he said that the oil press switch (#25036378) is longer carried. Hmmm.....????.....

 

[Just a Six??]

Try Glen at Nos4GN or Brian at GBodyparts

 

[j-6]

pumps

yeah get rid of the external if you had the HP you can buy an adopter and set both pumps intank run a hobbs switch and be lot more safe or at least thats what Im going to do my fuel pressure is dropping under boost Im running about 550HP they say the one 340 will do it but when you lots of mods like pulling lots of air the one pump just want do.

 

[Ttype6]

If that pump is good and you feel the need to get rid of it,get rid of it my way. My advice still is to keep it, Its a good pump. Do not run it all the time.

 

[Ttype6]

Called a buddy of mine that works the parts counter at a local Chevy dealership and he said that the oil press switch (#25036378) is longer carried. Hmmm.....????.....

Standard brand 2 part numbers PS140T-$5.17 PS140-$13.58

 

[Black3]

Check the A,B,C positions on the Caspers plug vs. the factory harness. Match up the colors (black to black and tan or grey to tan or grey) of the factory harness plug vs. the Caspers plug that goes to the pump. Mine didn't match and popped the fuse.

 

[Just a Six??]

Check the A,B,C positions on the Caspers plug vs. the factory harness. Match up the colors (black to black and tan or grey to tan or grey) of the factory harness plug vs. the Caspers plug that goes to the pump. Mine didn't match and popped the fuse.

Good Idea!!

 

[veedubcrazy]

Check the A,B,C positions on the Caspers plug vs. the factory harness. Match up the colors (black to black and tan or grey to tan or grey) of the factory harness plug vs. the Caspers plug that goes to the pump. Mine didn't match and popped the fuse.

When I tackled this job, I was replacing what was ripped out and gone. I will try the switcheroo with the wires and see what happens... Thanx...