[gregrob]

I installed a fuel pressure gauge tonight.
It is manual gauge and I just tapped into the 1/8 NPT port on the front of the pass side head and zip tied it outside the windshield for now.

Anyway, made some interesting discoveries.

Fuel pressure at idle is 75psi.
System is bone stock other than check valve removed from the front ds head when I installed the rubber line to clear the Terminator pumps.

Under WOT from a dead stop fuel pressure drops to 28psi!

If I roll into the throttle it doesn't drop much at all, but a dead stop with foot to the floor, it will drop about 15psi in 1st and 2nd and spike back up after shifts. It spikes back up after the 2-3 shift, then as 3rd winds out it drops like a rock!

It also takes a while for fuel pressure to come up when you turn the key on, like 15 seconds and the gauge slowly moves up to max psi.

My friends OBS on which we just installed an electric fuel system with a stock SD pump supplying snaps the gauge instantly to set pressure as soon as you turn on the key.

I have been having a cold start issue, the truck will fire off then die immediately, or won't fire off at all. It takes a while cranking 30-40 seconds minimum, then the truck will crank faster, faster, faster, faster, and finally start.

Today when looking for a place to install the fp gauge, my friend removed on of the BOSS O ring fittings from the fuel bowl and some fuel drained out.
We put that back in and installed the fp gauge in the head.

Well it took FOREVER for the pump to build up fuel pressure and the truck would not start! When the pressure came up, truck started exactly like it has been starting in the morning after sitting all night. faster, faster, faster, faster, finally lights the engine off and engine turns really slowly for a few seconds then comes up to normal idle RPM.

So, in your professional opinions, do I have a weak fuel pump? Or is it just not able to meet the demand of my comparitively small injectors?
If so, what is the cold start issue.

If I do need to replace the fuel pump because it's faulty, what should I use? Stock? Bosch 044 ?

Thanks for any input.

 

[CSIPSD]

Sounds like a bad pump... You should be able to hold 60 at WOT with a good pump... Mine is shimmed to 70 but drops to 60ish at WOT...

 

[69W900A]

For the money I'd put a 044 pump in. You can get them for about the same price as a stock pump, but they flow a lot more fuel. They are easy to install as they'll fit, snuggly, into the stock pump bracket.

You can find the 044's for around 200, sometimes less. I've seen them at local Bosch dealers here in town for 150-175 bucks.

 

[gregrob]

Thanks 69, I have my eye on that Bosch

 

[69W900A]

044 at 72 psi flows 53 GPH, and at 44 psi it flows 71 GPH. Can't remember what the stock pump flows, but it's not that much.

 

[CSIPSD]

WHat about two of them in series? Thats my plan... pre pump filter-lift pump-pressure pump- final filter...

 

[69W900A]

Series will only increase pressure. The two pumps in series will only pump as much volume as the weakest pump. In parallel you'll get the same pressure as one pump but more volume. You'll have to have one very big pickup (-10 or larger) or two separate lines for this setup.

One big line to a distribution block into two pumps, then the two pumps into another distribution block and one line up to the engine.

 

[gregrob]

Joe, run them parallel. I don't think series have worked out so hot for those who have tried it.

 

[gregrob]

Is this the right Bosch fuel pump guys?
http://cgi.ebay.com/ebaymotors/Bosc...ryZ33555QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

If any sponsors can get this, definitely buying from them. Just looking on ebay to see what I could find.

 

[69W900A]

Yep, that is the pump.

 

[CSIPSD]

Well thats not hard to do considering both the filter housings have two suppilys and two outlets...

 

[69W900A]

No, it's not hard. Just more plumbing to leak and more wiring. It will work fine to increase flow, but one larger pump will do the same thing. The 044 should flow enough fuel for most people's needs.

Not sure how much fuel the GTS injectors you have now will flow, you may need a larger pump than a single 044?

 

[CSIPSD]

220-225...

 

[jtharvey]

I'm very happy with my Bosch 044 pump. Granted, I do still have stock injectors (but only for a few more days ), but I can hold my set fuel pressure at WOT through every gear. I'll find out soon if it's enough to supply fuel to bigger sticks.

Edit: just looked at the eBay link. That's the place I bought my pump from, except direct from their website. They provided excellent customer service and quick shipping.

 

[69W900A]

I think the 044 should keep you supplied with #2 ok. You could run two factory pumps, but another factory pump is more than a 044 is. Or you can go for really big fuel and get something like an Aeromotive, but it's probably overkill.

 

[Tom S]

I would bet that one pump will address your issues Greg. I would be ordering one up today. That bosch pump was my backup option if my fuel systems would have not maintained enough pressure.

Tom

 

[Slated4Greatness]

Greg, just step up to the FASS 150/180.. Go big or go home..

 

[gregrob]

LOL Fiona, I'd love to.

Tom, I'm actually getting a SD pump from a friend, just to swap out and see what happens, but I am going to go with the Bosch I believe.


Ok update: This morning fuel pressure was really slow to come up, probably took 15-20 seconds to come all the way up, BUT truck still wouldn't start after fuel pressure came up.
Probably took another 30-45 seconds of cranking before it would light off. :shrug:

 

[PTSUPERD]

Greg, PM Lott about the pump I ran on my truck for a while. I cant remember, but I think the price was less than the one you found on Ebay. It supported my mini mes. I would still be running it if I had not bought the Fass.

 

[gregrob]

Well, what did you do with it? oke: