Fresh top end rebuild. Initial start & tuning. 1.7L D-Jet. Question about fuel line routing:

Does the fuel first pump through the pressure regulator? Lines come into the engine bay on the passenger side, snake over to the pressure regulator ---> then to the driver's side rail ---> then to the cold start valve attached to the front of the plenum ---> then to the passenger side fuel rail ---> then to the return line... I'm 99.9% positive this is the correct route but but with things not working quite right I want to neave no stone unturned...

Injectors are freshly cleaned/flow tested from Wichhunter.

The freshly rebuilt engine labors to start. Driver's side chambers are firing A-OK, passenger side is getting spark but no fuel flowing from the injectors. Checked one of the plugs and the passenger side has never seen combustion. Spark plug is as fresh and clean as when it was bought.

I had a wire pull out of the plastic plug that goes into the front side of the distributor (from the wiring harness). That was fixed by jamming the wire back in the plastic plug and keeping it in place w/silicone rubber. It's a low tech fix all 3 wires have continuity all the way through to the end of the plastic (where it plugs into the distributor).

Look at Dave Darling's drawing. I plumbed my system incorrectly when I tore out 100% of all the hoses and vacuum lines to reseal the engine.


Click to view attachment

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If BOTH your cyl 3+4 injectors are not firing, check the FI harness grounds at the back of the engine. Those 2 cyl share a common ground lug.

Thanks Brian. My setup does not have the cold start valve feeding from the middle of the fuel rail. Rather, it is part of the hose loop.

That diagram seems odd in that it has the pressure regulator at the end of the loop. I would think it would be at the beginning of the loop. I guess it does not act like a governor and limit what passes by. Rather, it must act like a dam, pushing back on the flow and allowing only a certain amount of the pressure past it.

I must have understood it wrong. I'm

Yes, the fuel line from the pump is pressurized to 29lbs by the fuel pressure regulator which the inlet is on the side. The lower pressure side is the straight out fittings back to the fuel tank.

Make sure you hook up the return to the return and the fuel pump outlet is to the fuel rail!!!!

sounds like a grounding issue our your trigger points are firing correctly maybe due to a loose wire?

Jeff - is the ground at the back of the engine you are talking about the one that comes off the bolt which goes through the case under the plenum? The male grounds are are part of an oversized washer.

It looks like Ray & Leo (board members - hooray N.E.W.!) may each have an extra harness which I can use as a test.

Thanks for your help.

-pt

Yes, that is the FI grounding block. It must be shiney clean and I use a dap of dielectric grease to improve/seal it and a dap on each push on.

Geoff -
I'm getting really good spark out of each wire at the distributor. Are the "trigger points" you are referring to the set that is in the lower part of the distributor (not what we usually call the "points")?

Dont go swapping harnesses just yet...you may just be changing problems.

Yes, the trigger points for the djet injector pulses. Pull the dizzy and check them for free movement as the grease does junkup and makes them stick.

Do you have a noid lite??? Stick that on the injector connections to see if they are all firing. If all are firing then the injectors are at fault. yeah, yeah I have read they are just cleaned and tested BUT they still might not be working!! Rich D can vouch for that BS as we went thru that on his car recently.

I checked the wires to the injectors. Grounds have continuity on each of the injector wire sets. On each set, I got nothing out of the second post. How would I test those second posts for pulse? I have a timing light, and multi meter. No noid light. Can anything else be made to work?

-pt

I dont think the trigger points are at fault here, simply because the trigger points affect the diagonal pairs, IE 2/3 and 1/4.. Jeff, does the ECU injector drivers fire in the same diagonal order, or is one of those drivers out?

b

Ill bring a fuel pressure gauge, think I have a noid as well. Regarding the fuel system, it should be right now. Think about it, the fuel pump is pushing gas... the regulator slows the flow to maintian pressure. There for the reg needs to be that last link in the chain. If its before.. then any thing past that will not have the proper pressure. Think one of the Jeff's were refering to the 3 white ground wires that connect to the rear center of the engine by the trunk fire wall. Let me know when you guys are meeting up again, and a list of possible components you might need.. I have a bunch of spares I can bring to test if you like.

If its the diagonal 2 cyl (1+4 or 2+3) not working its likely trigger points, because thats how they control pulses.

If the non-working cyl are on the same side of the engine, then it is likely the common ground connection for those two cyl.

I'm guessing the grounds are the problem. Both cylinders on the driver's side are A-OK (#1 & #2). It gotsta be something really simple like a ground but damned if I could find it when we were looking... Maybe a fresh set of eyes will spot something painfully obvious...

Tod - yeah, the regulator as the last link in the chain now makes sense to me. It acts like a dam, at least that's how I'm thinking of it.

-pt

pete i'm thinking it's those grounds28 and 29 under the plenum. i up for tommorrow night for as long as it takes.have fuel pressure guage.

Thats the FI ground cluster we are talkling about.. 3 spade clip/washer that is on a casehalf bolt. Needs to be super clean and bright so it makes good contact.

Might as well check your tranny ground strap too and make sure its clean.

Yeah, they worked before the engine was dropped but we all know how grounds can be pesky...
The stuff will get the good ol wire brush treatment...

-pt

i am definately no genius, but shouldn't the fuel flow the other way. fuel in then to the regulator? or is it just a 'wonky system that regulates on the out bound flow?

If pressurized flow went through the regulator first (before injectors), it would be 29 PSI on the pressure side of the regulator, but since there was nothing impeding its flow right back to the tank, basically 0PSI on its way to the injectors.

The regulator needs to be "downstream" of the injectors so they will "See" the 29PSI.

If the regulator is put before the injectors, it would also restrict flow to the injectors causing the them to not get the proper fuel amount it needs under load.

Here is what is should look like on yours. The way we had it last.
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java script:emoticon(':WTF:', 'smid_7')
java script:emoticon(':WTF:', 'smid_7')

tod - misfud - pics of the fuel & air hoses = outa sight.

on the pressure question - let's not forget what we already
know - thimk of garden hose. put a nozzle handle on the
end of it. to make things fun, in the middle - splice in an
extra nozzle ...& to make things scientific - tack on a pressure
gauge at each nozzle. now turn on the faucet. now you (this
expt takes 2 people) - alternately open & close your nozzles &
note your respective pressure readings. they will always coincide.
yup. hydraulic pressure works like that (thimk of the hydraulic
brakes = it matters not a whit who (front or back) - gets the feed
first = they both have the same pressure!)

long=story-to-short - the pressure regulator acts NOT like a dam
but as a bleed - when it looks at ITS pressure gauge - it opens
or closes as required to maintain its 29 (or 32 ???) psi.

daryl

That's Dave Darlings doing, can't take credit there . I just modified his schematic abit to fit what Pete had set up on his car. He has the cold start valve that has a "T" fitting on it so that the gas not only feeds it, but passes through. Thats the 1st time I seen a 1.7 set up, let alone a cold start valve like that.

well i'll be a suck-egg mule. i need to go back and look at the flow again. i may have it backwards. the odd this is; it seems to run decent. i thought it was just old intake boots.
hmmm, i wonder how much more power is lurking 'neath the cover.

thanks all

robin

1.8 and 2.0L Ljet buses have coldstart valves like that. Does it work?

ORIGINALLY A 1.7L!! 1972 1.7L. I've bastardized it over the years but the FI is fairly original (except for the replaced brain 10yrs ago, matching MPS 1yr ago, etc).

No 1.8L at all (w/exception to the heads...)

Geoff - I'm not sure if the cold start valve works or not. I guess now is a good time to check...

-pt

Richie (chef) and the others who said it was the ground were right on. One of the grounds under the plenum must have gotten pulled off b/c it was not attached - clear as day. Got it sorted and now we're firing on all 4 cylinders!

Now, the off season will def call for a revamping of the wiring harness... Those wires are so brittle and crack if sneezed on... One thing at a time...

-pt