Fuel pump is constantly running

turboyota · Post by **turboyota** » Sat Mar 11, 2006 10:30 am

Hey guys, I am having a problem with my fuel pump circuit. I am getting 5V out of the fuel pump pin 37 at all times when the key is on. However, in megatune it is cycling the pump as it should. I did some searching and couldn't find any solutions to this problem. Anyone know what is going on? Have any ideas?

I am using MSnS-E V2.2, MegaTune 2.25b717

Let me know if you have any ideas! Thank you.

keithmac · Post by **keithmac** » Sat Mar 11, 2006 1:24 pm

You should have switched ground at the fuel pump pin, somethings wrong on the board, are you definite the transistor`s fitted correctly?

woh · Post by **woh** » Sat Mar 11, 2006 4:16 pm

However, in megatune it is cycling the pump as it should

What do you mean by that.
The fuel pump turning on and off every second indicates a configuration error.

Please see FAQ on the Extra site at http://megasquirt.sourceforge.net/extra/faq.html

NOTE! You do not need to reload your firmware to fix this problem - just correct the offending setting.

Minami Kotaro · Post by **Minami Kotaro** » Sat Mar 11, 2006 4:26 pm

turboyota wrote:Hey guys, I am having a problem with my fuel pump circuit. I am getting 5V out of the fuel pump pin 37 at all times when the key is on. However, in megatune it is cycling the pump as it should.

Do you mean that, when the key is on but the engine is not running, the pump runs continuously? But MegaTune indicates that it cuts out as it should?

I would check the fuel pump relay first. I had this problem occasionally and it turned out my fuel pump relay was bad and would "stick" on.

turboyota · Post by **turboyota** » Sat Mar 11, 2006 4:28 pm

woh wrote:
However, in megatune it is cycling the pump as it should
What do you mean by that.
The fuel pump turning on and off every second indicates a configuration error.

Please see FAQ on the Extra site at http://megasquirt.sourceforge.net/extra/faq.html

NOTE! You do not need to reload your firmware to fix this problem - just correct the offending setting.

I meant it is cycling the pump, as in, it is turning it on to prime for a couple seconds, and then off again, and then on when cranking and running, etc. However, I am getting 5V out of the pin at all times.

woh · Post by **woh** » Sat Mar 11, 2006 9:07 pm

When you first turn on the ignition key the pump should come on to prime the pump and fuel lines and then turn off after 2 seconds.

When cranking the pump will turn on again and continue to run if there is rpm when you stop cranking. If there is no rpm when you stop cranking, then the pump will turn off. What you describe may be normal.

One side of the fuel pump relay should go to +12V. The other side goes to the fuel pump output of the MS. When MS is cranking or the engine is running the output of the MS should go to ~0V to activate the relay.

turboyota · Post by **turboyota** » Sat Mar 11, 2006 9:47 pm

woh wrote:When you first turn on the ignition key the pump should come on to prime the pump and fuel lines and then turn off after 2 seconds.

When cranking the pump will turn on again and continue to run if there is rpm when you stop cranking. If there is no rpm when you stop cranking, then the pump will turn off. What you describe may be normal.

One side of the fuel pump relay should go to +12V. The other side goes to the fuel pump output of the MS. When MS is cranking or the engine is running the output of the MS should go to ~0V to activate the relay.

Yes, I understand this...

In my MT, it shows that the pump output is doing this... BUT, I am getting +5V at all times when the key is on out of the fuel pump pin(37). Something seems to be wrong inside the box I guess, and I am wondering if anyone has seen this before.

keithmac · Post by **keithmac** » Sun Mar 12, 2006 7:07 am

Only problem I had was the solder pads contacting each other (bad soldering), you shouldn`t ever see 5v out of the pin, just gound when the fuel pump output is active. The Processor output is 5v, sounds like something`s wired in wrong on the board..

turboyota · Post by **turboyota** » Sun Mar 12, 2006 7:40 am

keithmac wrote:Only problem I had was the solder pads contacting each other (bad soldering), you shouldn`t ever see 5v out of the pin, just gound when the fuel pump output is active. The Processor output is 5v, sounds like something`s wired in wrong on the board..

Thanks, I didn't assemble the MegaSquirt, bought it assembled thinking it would eliminate problems like this

. I will have to open it up and take a look inside.

DGFTurbo · Post by **DGFTurbo** » Wed Mar 29, 2006 8:28 am

keithmac wrote:Only problem I had was the solder pads contacting each other (bad soldering), you shouldn`t ever see 5v out of the pin, just gound when the fuel pump output is active. The Processor output is 5v, sounds like something`s wired in wrong on the board..

What pads were bridged? Im having the same problem and i cant find any bridged pads.

turboyota · Post by **turboyota** » Wed Mar 29, 2006 8:39 am

DGFTurbo wrote:
keithmac wrote:Only problem I had was the solder pads contacting each other (bad soldering), you shouldn`t ever see 5v out of the pin, just gound when the fuel pump output is active. The Processor output is 5v, sounds like something`s wired in wrong on the board..
What pads were bridged? Im having the same problem and i cant find any bridged pads.

Yeah, I can't find any solder problems either. Did you assemble your MS yourself?

keithmac · Post by **keithmac** » Wed Mar 29, 2006 12:21 pm

2 pads on the fuel pump transistor were (just) bridged with solder, I didn`t assemble my board either..

First step would be to replace the fuel pump transistor and check it`s orientation I would have though?

turboyota · Post by **turboyota** » Wed Mar 29, 2006 3:04 pm

keithmac wrote:2 pads on the fuel pump transistor were (just) bridged with solder, I didn`t assemble my board either..

First step would be to replace the fuel pump transistor and check it`s orientation I would have though?

So, you fixed your problem? And you were having the same problem? 5V out anytime the MS is powered?

Thanks

DGFTurbo · Post by **DGFTurbo** » Wed Mar 29, 2006 7:10 pm

turboyota wrote:
DGFTurbo wrote:
keithmac wrote:Only problem I had was the solder pads contacting each other (bad soldering), you shouldn`t ever see 5v out of the pin, just gound when the fuel pump output is active. The Processor output is 5v, sounds like something`s wired in wrong on the board..
What pads were bridged? Im having the same problem and i cant find any bridged pads.
Yeah, I can't find any solder problems either. Did you assemble your MS yourself?

Yes I did

What transistor is the fuel pump circuit?

keithmac · Post by **keithmac** » Thu Mar 30, 2006 3:10 pm

Its Q3 on the v2.2 near the db37 connector.

I think had a constant ground problem with mine, never checked the output of the pin just had a close look over the board where the transitor sits.

DGFTurbo · Post by **DGFTurbo** » Thu Mar 30, 2006 4:31 pm

keithmac wrote:Its Q3 on the v2.2 near the db37 connector.

I think had a constant ground problem with mine, never checked the output of the pin just had a close look over the board where the transitor sits.

What about on the V3?
I should have mentioned im running MS1 V3

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Fuel pump is constantly running

Fuel pump is constantly running

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