Delco injection Esprit fuel pressure tester

[tomcattom]

I need to get fuel pressure test gauge to diagnose a potential fuel problem on my S4s. From reading around I believe the Schrader valve used on the Delco injection equipped cars uses a 7/16-20UNF thread on the valve.

I've found the Actron/Bosch CP7818 tester definitively state that it's compatible but is only available in the US and will take a couple of weeks to ship one here. Sykes Pickavant list one with the correct fittings but its priced north of £100 which seems a bit steep when I can import the Actron/Bosch for about half that if I'm prepared to wait. There are lots of cheap testers listed on ebay/Amazon which I can get next day with loads of adapters provided but none of them list any thread sizes for the included parts 🙄, at least for the sample of listings I looked at so far, so I have no idea if any of them will actually work with the Esprit. Anyone on here bought one of these sets and able to categorically say it fits on the Esprit's Schrader valved out of the box?

If not I guess I'll be waiting a couple of weeks for an Actron/Bosch gauage to travel over the pond because as far as I can see if the ebay/Amazon kits don't work the correct adapters are not readily available in the UK either.

[Chillidoggy]

What are the symptoms you’re experiencing? 

[CarBuff]

At the age of the GM fuel pump (and all the mentions of failures) I'd just replace the darn thing if you suspect ANYTHING fuel-pump-pressure related.

[tomcattom]

@Chillidoggy from a cold start, the car will fire up fine and then within a couple of seconds the revs completely die and it stalls out. Start it again and it runs absolutely fine thereon. Warm starts are absolutely fine and no obvious driveability issues noticed. I've tried key on priming couple of times before starting from cold and it doesn't make any difference.

New Sytec pump was fitted when the new alloy tanks went in back in March @CarBuff. However given the issues I had getting it to work from the outset part of me is wondering if there is in fact still a problem with the pump which I'm hoping a fuel pressure test will tell me.

[Chillidoggy]

It’s an easy check, maybe there’s someone nearby who has a test kit you can blag for a quick check? Any fault codes shown?

But if multiple key-ons have no effect, then it’s odd. I think a fuel pressure problem would probably manifest itself elsewhere, generally under load when demand is highest. I’ve got a secondhand spare PRV if you’re desperate.

[Sparky]

A standard cheap diesel test kit comes with the necessary size as default - no need to use any of the adapters.  I'm staring at mine right now!  Yours to borrow if you can get here quickly, as we'll be on a ferry in a few hours.  I could leave it with the mother-in-law with detailed handover instructions, but you'd probably get a cutlery set.

[tomcattom]

Nope, no fault codes, or at least no CEL light. That does assume that hasn't broken now too 🤣

I did run a capture on Espritmon from a cold start but couldn't spot anything that looked any different from a warm start that would indicate why it was stalling out.

I've got my new injectors to fit at some stage, but would be interesting to know what the fuel pressure is like before I do that. I have no problem buying one of those ebay/Amazon kits, but don't want to do it if I don't know that it will fit out of the box.

[tomcattom]

5 minutes ago, Sparky said:

A standard cheap diesel test kit comes with the necessary size as default - no need to use any of the adapters.  I'm staring at mine right now!  Yours to borrow if you can get here quickly, as we'll be on a ferry in a few hours.  I could leave it with the mother-in-law with detailed handover instructions, but you'd probably get a cutlery set.

Thanks for the offer @Sparky. I'm not in a major rush, but knowing that a basic diesel set will do the job I'll just procure one for myself. Any excuse to buy new tools 😁

[AndyPG]

4 hours ago, tomcattom said:

I need to get fuel pressure test gauge to diagnose a potential fuel problem on my S4s

Hi Tom,

This is the one I have

https://www.ebay.co.uk/itm/175247735798?hash=item28cd943bf6:g:yFkAAOSwQQxiXaDX

I checked the gauge before use and it was bang on.

The schrader fitting screws on perfectly just as Gary describes.

This will show your initial pre-start fuel pressure and running pressure which should be enough to see what's going on.

In order to do a fuel pressure/flow performance check, you would need Lotus tool T000T0910 in addition to the gauge set.

This is a blanking plug which is easily made on a lathe or I could lend you one.

When you fitted the new pump and tanks, did you discard the original pulsator?

Andy.

[tomcattom]

Thanks for the link @AndyPG . Kit duly ordered.

The pulsator was removed when the tanks were swapped and the new pump installed.

[AndyPG]

4 minutes ago, tomcattom said:

The pulsator was removed when the tanks were swapped and the new pump installed.

Cool, that rules that out then

Let's see what the gauge says.

Doesn't really sound like a fuel pressure issue though, considering second start is fine as are all hot starts.

More like an IACV problem perhaps?

Andy.

[Erikl]

Total shot in the dark....my S4 used to behave similar.  Over time and installing a BOV (getting that to work was suprisingly hard) I ended up getting rid of lots of the Vacuum demands.  And my car stopped behaving like that.

For instance I deleted the Charcoal Canister and the back pressure valve.  I also had a turbo waste gate sense line failure at one point.  

I hypothesize I fixed a small vaccum leak some where along the line.  I think this could show like an IACV problem possibly?  Wouldnt an IACV issue show on Espritmon?

Maybe disconect the Charcoal canister lines and plug to eliminate that system as an issue.  I guess as long as the one way valves on the vac lines are ok that should elimnate a failure there (now that I think about it)????  Lots of places to have a leak or an issue.  

 

[AndyPG]

23 minutes ago, Erikl said:

Wouldnt an IACV issue show on Espritmon?

Hi Eric,

The IACV receives step commands from the ECU but the IACV does not feed back any info to the ECU.

So the ECU never really knows for sure what the IACV doing, only what it is supposed to have done.

In theory, diagnosing a faulty IACV with Espritmon should be easy but, as with many of Esprit's foibles, there's always a strange puzzle involved.

I have read about so many similar issues which have been resolved by replacing the IACV, I have to admit it must be one of those enigmatic parts that can cause trouble that defies reason.

My next step would be to eliminate the IACV but, I agree with your thoughts...... I too was once logical like you.

In my third year of Esprit ownership, logic has been beaten out of me and I now go with the force.😥

Regards,

Andy.

[Erikl]

That is good to know about the IACV!  It seems like many issues could be linked to the IACV and I always thought it could show on the diagnostic programs.  

maybe I am thinking of the TPS, can that be seen on Esprit mon?

[AndyPG]

Hi Erik,

Espritmon does show how many counts the IACV has been sent by the ECU but the only evidence that the IACV is moving is in the idle rpm being on target (also visible on Espritmon) 

From reading the forums, problems arise from the IACV sticking, excessive play in the pintle shaft or the pintle being worn.

Obviously none of these are directly visible on Espritmon.

When I checked my IACV some years ago, the shaft was badly worn and was very wobbly but it still functioned.

I replaced it expecting an improvement in running, especially idle. The car ran the same.

But many people (including key forum members) have reported huge improvements which I acknowledge and have to concur with, even though Espritmon didn't point to it.

The TPS function is also visible in Espritmon but again, people have changed out TPS's that looked fine, only to find it resolved their issue.

I was thinking the other day that if I ever bought an old SE again, I'd replace all of the sensors, the IACV and the injectors on day one. Probably £700 to £1k worth of gear depending where you get it but imagine the peace of mind.

Well.....maybe......

Andy.

[tomcattom]

The IACV would appear to be functioning to some degree on mine, idle does adjust appropriately from cold, although it doesn't rule it out completely. I did remove and clean it earlier this year and adjusted the pintle length as per the manual.

Current plan is check fuel pressure and see what that reports when the tester arrives. Then I'll fit the new injectors and see what, if any, difference that makes and then diagnose further from there if the cold start issues persist.

[Barrykearley]

The IACV is a service item and caused untold issues on the vauxhall Cavaliers and Astras of the day way back when. 
They are about £15 from rock auto. The symptoms you are describing are exactly pointing to the IACV needing replacement.

[tomcattom]

Pressure tester arrived this morning. On single key on priming from stone cold it rises to 40psi and held steady there for a couple of minutes. I then started it and it rose further to about 46psi before its usual stall. Started again and ran fine, holding 46psi still. So the pump appears to be okay.

I'll fit the new injectors and see if that makes any difference, although if I'm honest I'm not expect them to solve the cold start stall, but they're being changed anyway.

Next task will be to source another IACV from over the pond since the consensus seems to be it's a wise shout to change it as a precaution if for no other reason.

[AndyPG]

Hi Tom,

With the ignition on, the initial pressure is ok at 40psi (spec is 40-47psi)

But when the pump stops, the pressure normally drops back a couple of psi before holding steady.

You say you were getting 46psi while idling. Was this at a cold 1200 to 1400rpm idle?

What pressure do you get with the engine idling at normal operating temperature (circa 1000rpm)?

The fuel pressure should be lower by 2.5-10psi when idling at op temp so maybe your fuel pressure regulator is on it's way out. This may or may not have anything to do with your starting issue though. Just an accidental spot? Check that the vacuum pipe to the FPR isn't leaking.

Andy.

Edited July 23, 2022 by AndyPG

[tomcattom]

The pressure did drop back a couple of psi after the initial prime @AndyPG, but assumed that was just a quirk of the gauge. Good to know that's expected.

The 46psi was a cold start high idle, not sure what the ECM was actually demanding, I didn't have my laptop with me, but it was probably nearer 1200rpm idle based on the rev counter. I never got it up to temperature because the running once warm hasn't been an issue, plus I changed the primary injectors today so didn't want to work on a hot engine in an already warm garage. I'll try and check the pressure when warm another day.

As I suspected might be the case the new injectors haven't resolved the issue, so I'll be waiting on the arrival of the new IACV next I think.

[AndyPG]

Hi Tom,

Have you checked that vacuum pipe to the FPR?

From memory, it goes to a little plastic T piece with another vacuum pipe coming off it. There's lots of scope for a leak here.

The fuel pressure at idle, even at fast idle, shouldn't be higher than the static pressure after ignition on.

The FPR (or associated vacuum pipes) is now prime suspect.

If the vacuum pipe to the FPR is in good condition and properly connected, I would order an FPR as well as the IACV.

Andy.

 

[tomcattom]

It stalled three times on start before it finally spluttered into life in the garage this morning, and the idle was a bit on the lumpy side, so I think it's pretty safe to assume the IACV needs replacing now.

Will inspect the vacuum hoses more closely later today.

[Barrykearley]

For the cost of said pipes in the engine bay - just replace them. Especially any rubber elbows. Don’t forget the ones under the dash 

[tomcattom]

New IACV arrived from PNM this morning - The price after shipping and import charges from the US meant the PNM price wasn't that much more and I get it next day. Interestingly however, the pintle is shaped slightly differently (no idea if that's because what they have supplied is wrong or what was already in there was wrong), but having fitted it it's made no difference to the cold start stall I'm getting and the idle once running still seems okay, as it was before I changed the IACV.

I haven't driven the car yet, but I did reset the BLM values with Espritmon before starting it and I did read something about a learning process running when over 20mph, so maybe once I get it out for a drive tomorrow it might improve then.

I've also got some silicone vacuum hose in the post that will hopefully get here tomorrow too 🤞

[Barrykearley]

That doesn’t look right at all.