[Dalsim007]

Had mostly resolved my FI issues last year except for that lingering bucking happening whenever the car was sitting still for a week unused. It will only stutter when under load and it would usually go away after a few hard accelerations once car was warmed up. Spark plugs were replaced late in the summer, which seemed to improve the run and reduced bucking. They were slightly fouled so I was thinking either the injectors could maybe be leaking when still or were a bit clogged up/lazy and once enough fuel was going through, it was making the issue go away...

I still had the original Bosch green/blue injectors from 1971 so I ordered a set of the equivalent Beck and Arnley ones. Made the swap and now the car has a slightly bouncy idle, whereas it did not before. On warm engine, loosening the idle screw under the intake opening helped somewhat but not much. Idle was still irregular even if RPM was going up. Even had some minor pinging when opening up the throttle on idle. Never had that. Is there something I should be adjusting with the new injectors in?

Tried a run around the street and the car was running terribly. Was bucking even worse than ever before. Pinging quite a lot under load too. Barely made it back. Double checked that all the injectors plug were well inserted (connected peg is slightly different on the beck n arlney so I made sure they were in. Tried with one fully off, car wouldn't even fire up, so I get that they are all firing...

Now back to the FuPu...Checked the fuel pressure, holds 20 psi with the pump switched on. And on idle was a steady 29-30 PSI. When opening throttle, it drops irregularly in the 24-26 range and bounce back up (assuming this is normal instantly after opening throttle?). Fuel filter has about 5k miles on it. As far as I know this is the original FuPu as well. Should I be repacing it?

Any way to check/reset the ECU unit knob to stock position? I had played a bit with it last year as I thought the car was running rich (fouled plugs). But it might have been caused by bad injectors?

Any idea on the FuPu behavious/testing or the beck and arnley injectors experience?

 

[Dalsim007]

Actually just took out again the plugs to verify, they are very black with a lot of soot... Cleaned them up. Runs nicer on idle, but after 20 mins idling, they are black again... Should I be changing the ECU adjustment on this finding? Where should the ECU idle mixture knob normally sit? Middle of the run?

 

[Dalsim007]

Oh well... So much for having a "volvo specialist" last year to adjust the TPS, while also providing them with the D-Jet service manual...
As I found out, the TPS lower contact was not even touching, leading to permanent enrichment I assume. Likely it was the cause for the fouled plugs, and causing over enrichment on acceleration. Strange that the issue would go away after a few hard acceleration (maybe after a while the plugs cleaned themselves enough to cope with the extra fuel?)

Maybe the old injector had obstruction/muck internally reducing the available fuel, making somewhat good use of the over enrichment...

I've temporarily adjusted the TPS so that the lower contact barely touches as per adjustment instructions in the manual. Will ensure tomorrow that the throttle stop is properly set up too. Hopefully this solves all bucking issues!

In the meantime, any insight on where the ECU rheostat knob should sit by default? middle?

 

[Dalsim007]

I did not mention, but my distributor was changed to a 123 ignition distributor quite a few years ago. Do you mean under the distributor cap where there is the rotor?

@142 Guy : The Beck and Arnley injectors do not appear to have pintle caps on them. I did use new matching set of seals on them (fat and small one on tip) when installing with a bit of dielectric lubicant. Should I have been moving the pintle caps from the old Bosch injectors?

 

[Dalsim007]

With regard to possible FuPu replacement. Noting that the 3 ports style on the 1971 is NLA. I see most vintage parts sites listing the Bosch #460900 as a replacement (looks like it is from the 240 cars?). Those being 2 ports, what is to be done with the third port hose? Can't seem to find any documentation on the conversion required to the two ports variant.

Those Bosch pumps seem decently priced. I figure it cannot be a bad thing to replace/retire the 51 year old Bosch three port unit...

 

[Dalsim007]

Dalsim;

...some disjointed notes after reading the thread, which I hope and expect you will be able apply...

...also, your ECU having the Idle CO adjustment knob means a late ('73?) D-Jet, but you should always state year and model and any deviations from stock setup when asking for help (I do see Ign changes, which when set to nominal should not affect of cause your issues).

Knob on (late) ECU only sets the mixture at Idle (so it is not the cause of what does sound like continuous rich running). I believe Green Book covers setting, which might need to be done with an exhaust gas analyzer...then again, when I went to my Dep of Mot Veh, to get my '73 ES inspected, the inspector (a former Volvo mechanic!) simply reached up and tweeked the knob saying (from memory) something like "...they ALL need to be set to two clicks off CCW"...I thought that was rather handy and fortuitous!!

I have not studied the early style TPS in as supergreat a detail as I have the later style, but electrically and functionally they are absolutely the SAME as far as the ECU goes, (only connectors to the outside world are inverted), but connector is keyed, so don't get distracted or confused by this (see: SW-EM D-Jet Idle Adjustment ). The info here is applicable: SW-EM D-Jet Idle Adjustment (17 [idle contact] MUST show continuity to 14 [ground/chassis] when Throttle is fully CW...if it does not, TPS adjustment is called for!) ...and in your picture, the "TPS lower [Idle] contact was not even touching [means the ECU NEVER knew it was at Idle!], leading to permanent enrichment I assume.(I'm not sure about that, because TPS does not do anything but inform ECU that it is at Idle, AND call for enrichment pulses when moving CCW...it does NOT inform ECU of absolute Throttle position, and so does NOTHING a steady Throttle position or when Throttle shaft is turning CW!...at steady Throttle pos, the Manif Press Sensor is the major mixture determining input to ECU!) ". I suggest you first assure TPS is functioning as expected using Ohm meter, then adjust its position on Throttleshaft per procedure...then you should be able to check that off your list, and move on to other troubleshooting...!

...the varying fuel pressure sounds suspicious, and reason for this needs to be ascertained and corrected! Rail pressure MUST remain constant at ALL times FuPu is powered, PERIOD! If you haven't changed FuFi, I'd change it, and inspect what(and how much) the old one has caught (often rust particles from Tank). See: SW-EM Bosch D-Jet Notes

I also agree with 142guy that increased rail pressure will cause a rich condition, but not lowered pressure, so that is due to something else (and Temp Sensor which makes the ECU think engine is still cold is often the cause).

I also recommend checking Injector volume and delivery...I like the safer method (no open fuel being squirted around at high pressure just looking for an ignition source!!) here: SW-EM Bosch D-Jet Notes

Good Hunting!

- ECU should be original to the car, which is a 1971. I have never changed it in 20 years of ownership, and bought the car with 57k miles. I would assume it is original based on that. I can confirm it has the adjustment knob for idle. Annoying as in my province there is no emission testing requirement, so I do not have access to a CO tester. Google just floods me with home or work safety gas alarms when searching. Found a Gunson G4125 Gastester which seems to do that, but not available anywhere apparently. Any idea on what might do the trick to measure emission alternatively? I might be missing the proper search keyword for it.

- TPS I confirm as you noted that it was enriching the mixture permanently. I'm thinking this is indeed the cause for the fouling of plugs. Car was running well, except a bit high. Was not able to lower it to 900 without it dying. Was running quite well on idle, but only if set to 1200 or so. That was after turning the TPS body CW until there was continuity between 17 and 14. To fully adjust the TPS, I will need to source a replacement screw for the throttle stop. Hoping the local hardware store may have something with matching thread pattern. It took a lot of lubricant and care to remove without snapping it (thank god to that induction heater rod I bought last year!). Philips head pattern was also damaged. Likely from when whoever messed with it many years ago. Locking nut was rusted badly on the screw shank too. I hope this will fully sort the high idle and rich running condition screwing plugs up.

- As for the fuel pump, I'm thinking it cannot hurt to replace it, even just because of its age. It does not appear rusted outside, or leaking from anywhere. It it loud however whenever I have not used the car in a while. I'm thinking the motor in it is starting to stick/seize (just like my blower fan motor) on startup, and once it ran enough, it gets back its power or something... Any thoughts on what changes are needed to accomodate the 2 port-style FuPu when replacing? Is it just removing the "T" connection on the return line and basically plugging the return line into the tank return port direct? Agreed it is counterintuitive that fuel rail pressure would be linked to my plugs issues. But it might explain the hesitation when accelerating once going. Given at that point, the pump is more solicited than at idle. It might we providing enough fuel at idle, but under load, it is showing its age...

 

[Dalsim007]

Dalsim;

"I'm thinking the motor in it is starting to stick/seize (just like my blower fan motor) on startup "
FuPu is a "wet pump" meaning fuel continuously runs through it cooling and "lubing", so it might be sluggish initially from fuel gum after a 20 year storage, but once going, fuel also serves to flush any gummage away...it also runs full bore at all times, pumping WAY more than called for at Idle.

Assure good electrical supply to Pump! Fuse 5 has been known to have a poor connection - all the way from slight R in series (clean those conical fuse contact areas to shiny metal, and treat with ACZP!), which would serve to drop SOME V, which FuPu would not get and therfore run slower/possibly sluggish, to fully OPEN such that FuPu does not run at all!!) Measure and check V... at Pump!...anything less than power buss V will certainly cause and explain a sluggish FuPu...sort this FIRST! Ref D-Jet Wiring for a '71: SW-EM Bosch D-Jet Notes ...so if your ECU has the Idle CO knob, which I believe only was on '73 possibly '72 ECUs, that suggests it has been changed, just as a sidenote...

...with VPReg regulating the Rail pressure and dumping any fuel beyond immediate demand back to the Tank...frankly, I don't think replacing the FuPu will buy you anything...my position is: If the pump is working (and not leaking, or doing anything else which might be a reason for replacing it), I would concentrate on the constant pressure requirement on the Rail...that is the main first requirement for a properly functioning D-Jet Sys! I'd plumb in a provision for checking Rail pressure (I've done this with an Oil Press Gauge...a bit "rustic" with it hanging out the back edge of the Hood, but just what you need during troubleshooting!...then there is NO question or doubt!...it allows monitoring and IMMEDIATE checking of the pressure under all driving and fuel demand conditions, including when intermittent symptoms occurred, which eliminated a lot of other unsubstantiated guessing!!).

Repeating: Rail pressure MUST remain constant at 28-30PSI (FPReg setting dependent), at ALL times FuPu is powered. PERIOD!

Good Hunting!

Definitely adding the voltage measure on the FuPu to the to do list. I did add in a gauge along the cold start valve when I adjusted the fuel pressure last year. With ignition on, but engne off, it stays on 20 psi. Engine on idle, the pressure is a steady 29-30 psi. When playing with the throttle cable, it is mostly steady, but drops to 24-ich range (if only for a split second as I turn the throttle valve). It corrects itself to 30 almost instantly. Are you saying it should not move at all ever, not even for a split second?

 

[Dalsim007]

Lucky that these older Volvos are all SAE. For once, they had the replacement screws I needed! Never happened when looking for the C30, S80 or S90!
New throttle stop screw and nut are in, new TPS locking screw are in too. I should receive a sec of gauge to measure that 0,5mm gap and conclude the TPS exploration tomorrow. Will try it all out on cleaned plugs and proprely reset TPS position.

@142 Guy: Yes the drop in the fuel pressure is very much a tiny half second thing. At any rate, I need to wrap up the evident enrichment issues before hunting for fuel pressure issues.

At all of you, you are such a previous source of knowledge! Can't express enough how much I appreciate your various tips and advice!

 

[Dalsim007]

Ron, I had cross referenced the ECU’s on Dr DJet, so given the source, hard to doubt. Agree that probably doesn’t have an impact on the current problem. But always good to “know what you have”.

Dalsim, are you sure the fuel is clean? No sediment in the tank and fuel filter doing it’s job? Would be worth a new, correct fuel filter: they’re different between the 70-71 and 72+. Also might be worth blowing out the fuel and return lines from front to back while disconnected. Do that outside. And how’s your ground strap from the bell housing to the frame rail? Worth cleaning those connections too, and some ACZP.

Engine and transmission grounds are good. I had replaced the fuel filter 2 years ago (about 5k miles on it) with the proper small filter for 1971 (previous mechanic had used a 1972-73 style big metal filter). Fuel lines and hoses were nice and clean at that time. Fuel tank was replaced also 7-8 years ago by a reproduction one. Can has run every summer since then, and was always winter stored with full tank and stabilizer in it. So I don't think the tank would be an issue on this.

Once ignition and TPS issues are sorted and if issue persist on bucking, I'll reach to Mike Dudek at IRoll. At 325 USD (with core refund), his rebuild 3 port original looks like the best way to go about it. Hopefully snow doesn't set up shop too early this December so I can still run around the street and sort it out before the deep slumber!!!

 

[Dalsim007]

Dalsim007, seems like you and I are chasing the same Gremlins (no offense to AMC).

I am using a Bosch 0 580 463 016 fuel pump in my 1971 1800E as a replacement for the original. It seems to be working fine if you consider using an alternative part. From the tank to the hose on the left in the picture, through the filter, through the pump, to the fuel supply line. Line coming back into the tank is from the fuel pressure regulator.
View attachment 174821

So you just removed the T split that was connecting the return line and coming the pump to tank connection. Now it is just return line to tank instead?

How is that pump for noise? Did you have to adapt the original clamp?

 

[Dalsim007]

Reviving this.
So summer started, and I finally sorted out the outstanding issues. Many thanks to everyone on this forum for their help.

After changing distributor cap and cables, the plugs (which were quite fouled) and the injectors during the winter, car was actually worse. Which made no sense. I was thinking to check the TPS switch again (had lubricated and cleaned it up last year, but not fully adjusted) as the contact plate wasn't super duper great.

I ended up going through the full adjustment from the book, and the result was the car was working even worse...
I did replace the fuel pump with a rebuilt one from Iroll motors although the pressure seemed fine on static, and so were voltage. I thought maybe when under load, it just wasn't ramping up. And it was quite loud and buzzy... I figured, after 52 years, it wouldn't make things worse to renew it regardless... Not surprisingly, new pump and new fuel filter didn't solve it.
It was not the culprit. It was definitely more silent, but car was still bucking under acceleration.

The final culprit was the 123 distributor. It had the wrong rotor inside (a volvo dealer had changed it when it snapped, and put the wrong one in there), and I found out that 5-6 years ago, the mechanic who installed the 123 distributor did not change the timing switch inside. So the car was programmed like a carbed car, with vacuum ADVANCE, whereas the B20E are supposed to have vacuum RETARD!!!! Made the switch to the proper map, and adjusted the timing properly on the distributor (10 BTDC) according to the book. And voilà! Car runs even better than my 2006 S80 and start instantly!!

Summing up everything at issue: previous car mechanic had fiddled and made wrong settings on:
-the fuel pressure regulator
-the distributor timing (123 distributor)
-the TPS adjustment
-the Throttle valve
-the idle pin

All of this tomake the car run somewhat ok, although rich...

The one true problem the car had originally: a blocked auxiliary air valve and difficult restart when hot (no phenolic washers at the time). When I fixed it with a repaired one, the bucking started. As the approximate countermeasure settings were now inappropriate.

In the end, chasing this issue, I finally sorted out all the gremlins.
Side benefit, I learned A LOT!
Car got renewed in a few areas, maybe not quite needed, but:
new injectors and seals, phenolic washers, new fuel hoses and rubber throughout, new plugs, new cap and rotor, new cables, new fuel pump and filter, cleaned and renewed TPS, new AAV (and spare money from rebuilding 7-8 of them for a few folks) and a renewed smile on my face and my kids face when driving!