75 280Z Hands -Free Fuel Pump Primer Circuit?

[HusseinHolland]

So, having driven the car to work Tues-Thurs, the starting time is not that bad. It's really only the cold start in 40ºF temps that is somewhat lengthy. I think I maybe being a little picky for an almost 50 year old drivetrain. I dunno. It's pouring rain today, and forecast the same for tomorrow, so Sunday I'll get back to it.

 

On 10/16/2023 at 10:37 PM, Zed Head said:

I looked around a little bit and it seems like the manufacturers generally went to computer control of a simple fuel pump relay instead of integrating the timer.  But it is a hot topic, so of course, people have filled the need.

https://www.ebay.com/itm/174274213748?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=NmzUBVTDRzy&sssrc=2047675&ssuid=bBzFtXzvTQO&widget_ver=artemis&media=COPY

This on Amazon, below.  The words in search should find it.  I don't like to copy their links they seem full of extra stuff.  Could probably be made to work.

 

Thank you Zed Head

The primer kit I knew about, as some Volvo PPL have used it. Personally, $70 for that is way too much, plus it's bulky (and tacky) 🤪 - so, I'll figure out a more discreet primer some way shape or form. 

 

[Captain Obvious]

I've toyed with this idea in the past and if I come up with a simple and elegant solution, I'll let you know. And I'm sure you'll do the same.

I've messed around with one of these little timer modules, and while it's overkill, it would work. Under ten bucks off ebay. One shot or continuous output. Programmable on time or off time. On pulse, or off pulse.

Moore's Law. Throw transistors at it.

Example ebay availability:
https://www.ebay.com/itm/334738777145?hash=item4deffc6439:g:WuoAAOSwc4FdeKyz&amdata=enc%3AAQAIAAAA4G9hgNdMy2ONBPE71Z3gGq3qzRvQaK%2BWxXTNH9UcLyqdQOnalj%2FTC7kXod2gRdFTsLiWo6%2Bw1CPybhOzekN701%2F%2BflwUhMM%2FPFwIW2dw8osWQx9N5Y%2Bzkpow7cdoPTmHLYpoPfIk%2FRFNVEEBRJsPYuXmY4ugTqfGWpl7Ec4CWDHRZSS741ZOWEezeh8wGXqgvZyp08MiOeeLydivakdTYNtrBhLn%2F0TIsZKVjDUwYSL53goggea6rIRywsYDHcrtu5vM73hwhkBkbaBkKp%2FbkO65VxtF9cypNMy2%2BfSyOCw%2B|tkp%3ABFBMrtrs_Oli

[HusseinHolland]

On 10/20/2023 at 9:18 PM, Captain Obvious said:

I've toyed with this idea in the past and if I come up with a simple and elegant solution, I'll let you know. And I'm sure you'll do the same.

I've messed around with one of these little timer modules, and while it's overkill, it would work. Under ten bucks off ebay. One shot or continuous output. Programmable on time or off time. On pulse, or off pulse.

Moore's Law. Throw transistors at it.

Example ebay availability:
 

I did order one like that - with a case, about $4. I'll wire it in the AFM pump switch circuit. As an aside, with the proper cranking speed back, the startup times hot or cold are very much improved.

[Captain Obvious]

Yeah, I wouldn't have even suggested it since it's such overkill (and not "small and simple"), but it's just so cheap. 

So I'm assuming there are a bunch of different varieties, but the one I had here did one shot with variable pulse width. If yours has that mode, you should be good.

[darom]

@Captain Obvious Any updates on your fuel pump-priming project? I use one of those $5 time relay boards to run a 1979 fuel rail fan blower for 10 minutes. It is manually operated. The relay board is attached to a bigger relay to handle the load of the blower motor.

[Captain Obvious]

@HusseinHolland is working on the fuel pump primer. I'm just supporting cast.   

[HusseinHolland]

I'm going to add the relay - it's just a bit of a PITA to work with the relay end of the FI harness in the space under the dash. I really should have thought about this while the dash was out. Hindsight is always 20/20.

I'm going to add a bridge harness to take the AFM pump trigger, run it through the timer relay, then back to the factory relay.  So, I need to extract the trigger wire from the existing relay socket. The constant and switched power for the timer can also be drawn from the main relay, to avoid running lengths of new harness from other sources.

It would be possible to make an entirely plug & play insert to redirect as needed from the factory relay sockets, however that would end up occupying much more space up under there, which I really don't have now that I added the 2 adjustable flasher relays.

Working on my back and/or twisted up under the dash is not good for my lower back issues, so in part I am avoiding it for that reason. I will get to it eventually. 

[darom]

Thanks for looking into it! I have the same issue, I am running the MSD-2225 fuel pump, and I think it doesn't have any drain-back valve. I installed one of those Amazon special one-way valves after the fuel filter in the engine bay. After a while, it stopped working. When I took it apart, some corrosion inside created the seal/membrane gaps.

What do you think about wiring the fuel pump relay + 5-10 sec timer relay into the ignition switch (ON position)? The fuel pump wires run under the carpet on the passenger side (at least in my 76), providing an easy access.

[Zed Head]

9 minutes ago, darom said:

MSD-2225 fuel pump, and I think it doesn't have any drain-back valve.

It should.  Most do.

The old original FPR's are known to leak down.  It just takes a little bit of rust at the seat surfaces.

[darom]

Found this link to a pre-made timer relay to get some cheaper build ideas: http://www.okaauto.com/EFITimer.html

Edited November 25, 2023 by darom

[HusseinHolland]

1 hour ago, darom said:

Found this link to a pre-made timer relay to get some cheaper build ideas: http://www.okaauto.com/EFITimer.html

That's not cheaper than the $5  programmable relay. It still has to be (self) wired into the car, it's not plug & play 

[Zed Head]

Here's some expensive examples.  Is the goal cheap, effective, or both?

https://www.delcity.net/productsearch?search=time+delay+relay&x=0&y=0&it=