Mondial 83 QV "fuel pressure regulator" Question

I owned an 85qv. Get the thin yellow Bosch k jetronic" book. It is detailed enough for basic understanding of the units MO. Every owner can benefit. It's got good pics and diagrams

 

Fuel pressure acumulator is next to the fuel pump. When it leaks on the floor time to change it (except in California where the cars are equiped with a return line that "collects" the leak).

Fuel pressure regulator is within the distributor (the grey part with many 8mm fuel lines feeding the injectors). The acumulator cannot be serviced.

WUR is the regulator for the "control pressure" regulator. (K-JET uses two pressures, one for the whole system, one for control).

Both the distributor and WUR can be serviced ($60 worth of gaskets and parts).

 

No, your post contains three different parts, and, unless you are restoring a car that has sat unused for many decades, there is a very low likelihood that all three would need to be replaced -- i.e., if you had a car that was running fine and then suddenly developed a runability problem = more likely just one component has a problem and you need to do more diagnosis to determine which part is the culprit.

By who? If this is just a list of many people throwing out random possibilities for what might by the bad component = you know nothing about what needs to be replaced. .

The three different components in your post are:

"Fuel Pressure Regulator" = this is a subassembly inside the fuel distributor.

"Warm-Up Regulator (WUR) " = these two are the same component just called different names.
"Control Pressurer Regulator"

Bosch Accumulator - 0438170004 = this is a separate component.

Do you have a copy of the 281/83 Mondial8/QV WSM? Section D (exactly) describes how the Bosch CIS K-Jet without Lambda system on any 1983 MondialQV or 308QV (both US version and euro version) operates and its components. If not, you can get a pdf copy of 281/83 here:

https://www.dropbox.com/scl/fi/twng41f9fpi3ipww7q95v/Mondial8qv_workshop_281-83.pdf?rlkey=5sgpj4yz33jepzrec4x8lcwel&st=4o2n8ksm&dl=0

 

The most likely cause for this symptom is the residual fuel pressure falling too quickly after warm engine shut off -- that's what should be measured BEFORE buying any components. If that is the issue, the suspects are (and the order that I'd investigate is):

1. Leaking Accumulator -- as raemin stated, liquid fuel will leak out the vent nipple if the Accumulator is bad (when the engine or fuel pump is running). On the euro version, this is immediately obvious as the vent nipple is left open to atmosphere. On US versions, they added a hose on the vent nipple that goes back to the tank -- this hose has to be removed to check for any liquid fuel. If there is no liquid fuel coming out the vent nipple = almost certainly, the Accumulator is OK. If there is liquid fuel = replace Accumulator.

2. Leaking fuel pump check valve -- no good way to test this without just replacing the fuel pump (if you've already confirmed the Accumulator is OK). One "complication" here is there are two different fuel pumps: the original stock one (Bosch 69523) has a built-in check valve; however, this can be difficult to source so can be replaced by the later Bosch 69532, but that later fuel pump has an external check valve that requires changes to the hose plumbing. We've had many instances of people replacing the early style fuel pump with the later style fuel pump and wrongly leaving the check valve out completely. Additionally, many F of this era were updated (either correctly or incorrectly) to the later style fuel pump as the early style fuel pump was not available for many years. So the first thing you need to do is determine is which fuel pump is on your car and, if updated, was it properly done, or not. If you can post a picture of your fuel pump assembly, that can be determined easily.

3. Bad o-ring(s) in the fuel pressure regulator section of the fuel distributor -- this is more complicated, and you (and I) don't need to go there unless #1 and #2 have already been done, but the residual fuel pressure is still falling too quickly.

 

While you investigate the issue, you can trick the hot-start mecanism as follows:

1) floor the throtle pedale while cranking.

2)last resort disconnect the safety switch (bosh junior plug) from the distributor.

At least you will not be stranded (this will force the pump to operate and will let you start the engine).

 

You're welcome, and thanks for the kind words. Now your responsibility is to not ghost us, and let us know what you eventually find is the problem and what was done to correct the problem.