Deatschwerks check valve install = Fix for hot start up issues

[NGOT8R]

Some of you may remember a while back, that I made a thread regarding the failure of the factory fuel pump in my 2019 Bullitt at 7K miles. This failure resulted in me upgrading to a Deatschwerks DW400 fuel pump. While the pump upgrade fixed the fuel flow issue, it also revealed a new issue (difficulty starting when engine was warm). Let me explain: Whenever I turned the engine off after a drive, it was always hard to start up again. The engine would fire, stumble and die 2-3 times, unless I managed to save it, by applying throttle, after which it would settle into a smooth idle with no further issues.

I finally grew tired of the annoyance and fixed the problem by installing a Deatschwerks -8AN check valve in the factory fuel line. Not only did this take care of the problem, it increased pump priming pressure as well. Normal fuel flow pressure at idle is between 80-83 psi.

Some of you may ask, why was this necessary if Deatschwerks began selling their pumps with preinstalled check valves in them in 2019? Well, in my case, I didn’t buy my DW400 pump directly from Deatschwerks and therefore, I ended up with an older version that I presume had been sitting on the vendor’s shelf for a while, until I came along and bought it. Hopefully this information will be of help to the next person, who may be experiencing this issue.

Links to parts needed to perform the install:

https://www.amazon.com/dp/B081Q9HFYJ?psc=1&ref=ppx_yo2ov_dt_b_product_details

https://www.amazon.com/dp/B0BZL5V4MD?ref=ppx_yo2ov_dt_b_product_details&th=1

https://www.amazon.com/dp/B08SQ6M8CZ?psc=1&ref=ppx_yo2ov_dt_b_product_details

https://www.amazon.com/dp/B0BLLW452Q?ref=ppx_yo2ov_dt_b_product_details&th=1

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[MiamiGT350]

Thank you for the useful info and part links!

 

[Spock5.0]

Glad to see you were able to resolve the hot start issue. Still haven’t gotten around to ordering my dw400 yet because I just haven’t had the time, and still on the fence about if I need to do a hardwire kit for the upgrade. Already have a sub power wire running from the batt, and just haven’t felt like pulling interior panels again to run another one, nor do I have the time for all that right now.

 

[NGOT8R]

Glad to see you were able to resolve the hot start issue. Still haven’t gotten around to ordering my dw400 yet because I just haven’t had the time, and still on the fence about if I need to do a hardwire kit for the upgrade. Already have a sub power wire running from the batt, and just haven’t felt like pulling interior panels again to run another one, nor do I have the time for all that right now.

No need hardwire the DW400, it’s literally a plug and play unit as far as the wiring goes.

Is there any particular reason as to why people would want to hardwire it?

 

[Spock5.0]

My assumption would be concerns regarding additional amperage draw and whether or not the stock wiring is up to the task to be able to deliver proper voltage.

As a side note to my issue, I ended up just buying an oem unit out of a wrecked car on eBay since I’m not boosted as of now. Should be here today. So hoping that solves my issue, though admittedly, I did some diagnosis last weekend and the car idled in the driveway for about 15mins, and then I drove around my neighborhood with no issue. So idk if it’s an electrical issue, or the pump is on its way out and just acting ok temporarily. So I’ll still swap it for the replacement unit and hope that solves the issue.

 

[mejohn50]

My assumption would be concerns regarding additional amperage draw and whether or not the stock wiring is up to the task to be able to deliver proper voltage.

I am, along with others, running a DW400 and an 18v BAP on stock wiring and fuse. I’ll admit, the BAP is pushing things pretty hard on stock wiring, but it does work fine.

@engineermike might be able to share some more info regarding current draw with a few different configurations including the DW400.

 

[engineermike]

I have all the amp draw numbers for stock and dw400 at different voltages. The dw400 amp draw can be 27-33 amps at 22 volts. But the way a bap works is that it pulls 22/12 times this through the stock wiring. I’ve pulled as much as 46 amps through the stock wiring and 40 amp fuse, albeit for a short period of time. Yes, if you look at amps vs wire size it doesn’t meet any sort of code requirements but cars don’t generally follow nec probably due to the duration at these loads (seconds vs years). Myself and others have run 18v on a dw400 for years now.

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