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Qavion

Fuel Pump Fuse Holder (Melted)

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Couldn't start my '89 SE this evening. I found that the fuel pump fuse and the plastic holder had melted (not sure why, except there was a 15Amp fuse in there and my manuals say 10Amp). The pump is standard. The injectors are from WC Engineering.

 

The holder is a stackable type. I'm having trouble finding an indentical part online.

 

 

FuelPumpFuse2.jpg

 

FuelPumpFuse3.jpg

 

Any suggestions?

 

Thanks

Cheers

Ian

Edited by Qavion

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Upgrade today to remove Google ads and support TLF.

I'd be checking every single connection in the fuel pump circuit and then pricing up the cost of a replacement pump.

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I'd be checking every single connection in the fuel pump circuit and then pricing up the cost of a replacement pump.

 

 

That's a worry...  I can't have more than 15,000km on this pump.

 

I'm a little puzzled at why the fuse simply didn't break to stop the current flow. Would this be due to relatively high current flow for long periods, melting the plastic before it melted the fuse?

 

 

 

Thanks, Sanj, but the orientation of the plastic lugs (for stacking the relays) seems different. The wires would point towards the bulkhead. Of course, I can use anything as a temporary fix, and attach the holder with zipties, but I'd prefer it to look the same as the next one.

 

Cheers

Ian. 

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The failure is probably due to a poor connection of the fuse causing a high resistance that resulted in the heat.

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Just my 2 pence worth some fuses can blow in a way which makes the two pole Ie the thick bits fold in together making a 10 amp fuse more like an 80 amp if you had a short the fuse could have blown but melted together creating a larger problem thus heating the area and melting the holder .

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Thanks gentlemen. All clear now. 

 

Much appreciated.

 

Cheers

Ian

 

(EDIT) I've ordered a pump just in case, but in the meantime I'll check the current being drawn by the pump, both on startup and normal operation.

Edited by Qavion

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The fuse holder seems to be taking its time to arrive, so I thought I'd change the fuel pump anyway. I bought a kit from Lotus Marques (Australia): It comes with a Bosch pump, an electric adaptor cable (no plug change required), fuel pump filter, fuel-immersible hose and p-clips, pump sleeve and a plastic collar for matching the pump to the base of the assembly.

 

http://www.iinet.net.au/[email protected]/Lotus/FuelPumpKit.jpg

 

I'm just wondering what holds the new pump into the base of the assembly frame. On the old setup, it just seems like the anti-pulsation device was holding the pump in alignment./position. On the new pump, only the rigidity of the fuel-immersible hose seems to be holding everything in place. Would you recommend plastic zip ties to hold the pump to the assembly frame? If so, are they normally fuel resistant?

 

And what is that item marked with the "?" in the photo? I'm not sure if I should fit it with the new pump. I don't know if it adds an element of rigidity to the original pump assembly.

 

Thanks for any insight.

Cheers

Ian.

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Update: actually, once fitted, I discovered that the fuel-immersible hose is quite rigid and will probably hold the pump in the frame (assuming the fuel doesn't soften the hose in time).

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Out of curiosity did you measure the current draw of the old pump to see if it was to blame for the melted holder?

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Out of curiosity did you measure the current draw of the old pump to see if it was to blame for the melted holder?

 

 

To be honest, I wasn't willing to risk incinerating what was left of the old wiring. I guess I could attach it directly to the battery with some spare pieces of wiring (not submerged in fuel though). Unfortunately, the injectors are in parallel with the pump, so I probably wouldn't get a normal current reading.

 

I replaced the fuel pump relay, too, in case that had some kind of short it in.

 

Do injectors use much current? Is it possible for them to short out?

Re the fuse being 10amps, I was looking at an earlier car's diagram. It should be 15amps (as was installed).

 

Cheers

Ian.

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Thanks, Derek.

 

Apart from a starting problem (which I attributed to a flattish battery), there were no running problems. I do get the occasional stall when the engine is cold. I'd move the car out of the garage, get out of the car to close the garage door, get back in the car, then go to drive off. The car would die as I moved off (ok on restart, fine thereafter).

 

I've changed the IAC at least twice.

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Update: the fuse holder finally arrived from the USA (17 days since I ordered it) and found it didn't fit onto the relay and other fuse holder. Quite a bit of filing required to make it fit.

And I've just realised that I don't have anything to measure more than 10 amps. Now I have to wait for a clamp meter to arrive in the mail. I think I'll buy a fire extinguisher in the meantime :P

 

Cheers

Ian.

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I'm wondering if anyone else has some current readings for the pump (and injectors) on an SE/S4?

 

I put the ignition to on (not start) and took an amperage reading of the new Bosch pump. It was only 3.3 amps before the pump automatically switched off (as it should). I used a digital ammeter in parallel with a shunt resistor (bought as a set on eBay for a few dollars). This setup can measure up to 50Amps, but I'm not sure if it needs calibrating before use.

 

The car runs well, but I'll buy an ammeter which fits directly in series with the pump (and injectors) and take another reading. I'll also buy some leads so I can check the old pump straight off the battery.

 

The new pump is much quieter than the original has ever been and I'm not sure I could hear it running in the driver's seat (windows wound down and tailgate open). It could have been my electric chargecooler pump making all the noises.

 

The electrical connector plugs on the pump which are submersed in fuel look far from liquid-proof. Is it normal for exposed wires carrying this sort of current to be submersed in fuel? I was waiting for a big bang when I switched on the ignition :P

 

Cheers

Ian

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The primary injectors are "peak and hold" which means they can peak up to ~6A each for a brief moment.  Which would also make it fairly difficult to measure current draw, unless you have a fast meter.

 

How is your electric chargecooler pump wired?

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The primary injectors are "peak and hold" which means they can peak up to ~6A each

 

 

Thanks, Travis.

 

"... and hold"? 6 x 4 is 24amps, well above the 15amp fuse rating.

If I can confirm my LCD ammeter is working properly by comparing it to an analog meter (on order), I should be able to get fairly instantaneous results.

 

How is your electric chargecooler pump wired?

 

 

If I remember correctly, I wired it up to the throttle jacking capsule plug (Throttle jack disabled)

 

Cheers

Ian.

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all 4 injectors don't fire at the same time, only 2 per event.

 

It should be wired to the EBPV, the throttle jack turns off once the engine is warm.. You wan the opposite behavior.  The EBPV turns on with the key, off while cranking, off until warm, and then stays on for the rest of the drive while the engine is warm.

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ah... that sounds familiar. It probably is the EBPV. I haven't checked how I wired it up recently... but the chargecooler stays cool.

 

Thanks, Travis.

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